California: Individual County Chronologies
California Atlas of Historical County Boundaries
John H. Long, Editor; Peggy Tuck Sinko,
Historical Compiler; Laura Rico-Beck, GIS Specialist and Digital Compiler; Peter Siczewicz,
ArcIMS Interactive Map Designer; Emily Kelley, Research Associate; Robert Will, Cartographic Assistant
Copyright The Newberry Library 2003
25 Mar 1853 ALAMEDA created from CONTRA COSTA and SANTA CLARA. (Calif. Stats. 1853, 4th sess., ch. 41/pp. 56–59)
30 Mar 1874 ALAMEDA gained small area in San Francisco Bay from SAN FRANCISCO; placed all of the Central Pacific Railroad Wharf in ALAMEDA. The wharf was removed in 1919 [for location see 1874_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, pp. 168–170; Coy, 62–63)
14 Mar 1878 Boundary between ALAMEDA and SAN MATEO in San Francisco Bay was adjusted [not mapped]. (Calif. Stats. 1877, 22d sess., Acts Amendatory of the Political Code, ch. 197/p. 71)
14 Jan 1958 ALAMEDA gained small area from CONTRA COSTA [for location see 1958_pt.shp; change too small to display on interactive map]. (Coy, 338–339)
02 Nov 1971 ALAMEDA lost small areas to SANTA CLARA [for location see 1971_pt.shp; change too small to display on interactive map]. (Coy, 338, 343)
01 Sep 1992 ALAMEDA gained small area from CONTRA COSTA. Ordinance passed 11 August 1992; effective 1 September 1992 [for location see 1992_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Alameda County, 11 August 1992, ordinance 92–57)
11 Oct 1993 ALAMEDA boundaries restated to incorporate 1 September 1992 change [no change]. (Calif. Stats. 1993–1994, reg. sess., ch. 1195, sec. 2.5/p. 6853)
04 Oct 1995 ALAMEDA lost small area to CONTRA COSTA [for location see 1995_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1995, reg. sess., ch. 529, sec. 3 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002)
19 Aug 1996 ALAMEDA boundary clarified [no discernible change]. (Calif. Stats. 1996, reg. sess., ch. 400, sec. 4 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002)
16 Mar 1864 ALPINE created from AMADOR, CALAVERAS, EL DORADO, MONO, and TUOLUMNE. (Calif. Stats. 1863–1864, 15th sess., ch. 180/pp. 178–182)
17 Nov 1995 ALPINE gained small area from AMADOR. Ordinance passed 3 October 1995; effective 17 November 1995 [for location see 1995_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Amador County, 3 October 1995, ordinance 1390)
14 Jun 1854 AMADOR created from CALAVERAS. Act passed 11 May 1854; referendum for or against creation of the new county held 14 June 1854. (Calif. Stats. 1854, 5th sess., ch. 42/pp. 45–48)
16 Apr 1855 AMADOR gained from EL DORADO. (Calif. Stats. 1855, 6th sess., ch. 92/p. 113)
23 Apr 1855 AMADOR boundaries redefined [no change]. (Calif. Stats. 1855, 6th sess., ch. 113/p. 134–135)
25 Apr 1857 AMADOR exchanged with EL DORADO. (Calif. Stats. 1857, 8th sess., ch. 220/p. 251)
08 Apr 1863 AMADOR gained from EL DORADO. (Calif. Stats. 1863, 14th sess., ch. 170/p. 231)
16 Mar 1864 AMADOR lost to creation of ALPINE. (Calif. Stats. 1863–1864, 15th sess., ch. 180/pp. 178–182)
02 Mar 1866 AMADOR lost to MONO the remnant of territory that was left separate from AMADOR by the creation of ALPINE. (Calif. Stats. 1865, 16th sess., ch. 161/p. 144)
30 Jun 1991 AMADOR gained small area from EL DORADO. Ordinance passed 25 June 1991; effective 30 June 1991[for location see 1991_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, El Dorado County, 25 June 1991, resolution 211–91; Minutes of the Board of Supervisors, Amador County, 12 June 1990, resolution 90–182)
17 Nov 1995 AMADOR lost small area to ALPINE. Ordinance passed 3 October 1995; effective 17 November 1995 [for location see 1995_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Amador County, 3 October 1995, ordinance 1390)
BRANCIFORTE (see SANTA CRUZ)
30 Apr 1855 Legislature authorized creation of BUENA VISTA (proposed) from TULARE; creation did not take effect. (Calif. Stats. 1855, 6th sess., ch. 161/pp. 203–205; Coy, 15–16)
16 Apr 1856 Legislature authorized BUENA VISTA (proposed) to gain from TULARE, even though the creation of BUENA VISTA (authorized 30 April 1855) had never gone into effect. [Proposed change not displayed on interactive map; see "Special Topics."] (Calif. Stats. 1856, 7th sess., ch. 81/p. 96)
18 Feb 1850 BUTTE created from non-county area. COLUSI (now COLUSA) not fully organized, attached to BUTTE "for judicial purposes." (Calif. Stats. 1849, 1st sess., ch. 15, sec. 21/p. 62)
10 Jan 1851 COLUSI (now COLUSA) fully organized, detached from BUTTE. (Rogers, 57–61)
25 Apr 1851 BUTTE gained from SUTTER, lost small area to SHASTA. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 21/p. 177)
03 May 1852 BUTTE exchanged with SUTTER. (Calif. Stats. 1852, 3d sess., ch. 149/p. 237)
19 Mar 1853 BUTTE boundaries clarified [no change]. (Calif. Stats. 1853, 4th sess., ch. 37/p. 53)
31 Mar 1854 BUTTE lost to SUTTER. (Calif. Stats. 1854, 5th sess., ch. 16/p. 26)
01 Apr 1854 BUTTE lost to creation of PLUMAS. (Calif. Stats. 1854, 5th sess., ch. 1/pp. 129–131)
09 Apr 1856 BUTTE lost to creation of TEHAMA. (Calif. Stats. 1856, 7th sess., ch. 100/pp. 118–119)
19 Apr 1856 BUTTE lost to COLUSI (now COLUSA). (Calif. Stats. 1856, 7th sess., ch. 105/p. 124)
21 Apr 1856 BUTTE lost to SUTTER. (Calif. Stats. 1856, 7th sess., ch. 150/p. 231)
19 Apr 1859 BUTTE gained from TEHAMA. (Calif. Stats. 1859, 10th sess., ch. 322/p. 359)
22 Mar 1860 BUTTE lost small area in village of Strawberry Valley to YUBA [for location see 1860_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1860, 11th sess., ch. 145/p. 115)
15 Apr 1861 BUTTE lost small area at Woodville to YUBA [for location see 1861_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1861, 12th sess., ch. 166/p. 167)
01 Apr 1864 BUTTE lost to SUTTER. (Calif. Stats. 1863–1864, 15th sess., ch. 292/p. 301)
01 Jan 1873 BUTTE gained from COLUSA. (Political Code 1872, 1: secs. 3916, 3922/pp. 119, 123–124)
07 Mar 1874 BUTTE boundaries clarified [no change]. (Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, p. 167)
25 Feb 1897 BUTTE exchanged with YUBA. (Calif. Stats. 1897, 32d sess., ch. 26/p. 22)
23 Mar 1901 BUTTE exchanged with PLUMAS. (Calif. Stats. 1901, 34th sess., ch. 146/pp. 549–551)
08 Aug 1915 BUTTE gained small area in section 3, township 19 north, range 1 east from GLENN [for location see 1915_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1915, 41st sess., ch. 532/p. 898)
20 Nov 1944 BUTTE exchanged with TEHAMA. (Coy, 339, 345)
18 Feb 1850 CALAVERAS created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 25/p. 63)
18 Apr 1850 CALAVERAS boundaries clarified [no change]. (Calif. Stats. 1849, 1st sess., ch. 111/pp. 262–263)
25 Apr 1851 CALAVERAS boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 13/p. 175)
14 Jun 1854 CALAVERAS lost to creation of AMADOR. Act passed 11 May 1854; referendum for or against creation of the new county held 14 June 1854. (Calif. Stats. 1854, 5th sess., ch. 42/pp. 45–48)
19 Apr 1856 CALAVERAS lost to creation of FREZNO (now FRESNO). (Calif. Stats. 1856, 7th sess., ch. 127/pp. 183)
24 Apr 1861 CALAVERAS lost to creation of MONO. (Calif. Stats. 1861, 12th sess., ch. 233/pp. 235–236)
16 Mar 1864 CALAVERAS lost to creation of ALPINE. (Calif. Stats. 1863–1864, 15th sess., ch. 180/pp. 178–182)
18 Feb 1850 COLUSI (now COLUSA) created from non-county area; COLUSI not fully organized, attached to BUTTE "for judicial purposes." (Calif. Stats. 1849, 1st sess., ch. 15, sec. 22/p. 62)
10 Jan 1851 COLUSI (now COLUSA) fully organized, detached from BUTTE. (Rogers, 57–61)
25 Apr 1851 COLUSI (now COLUSA) gained from YOLO, lost to SHASTA. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 29/p. 179)
09 Apr 1856 COLUSI (now COLUSA) lost to creation of TEHAMA. (Calif. Stats. 1856, 7th sess., ch. 100/pp. 118–119)
19 Apr 1856 COLUSI (now COLUSA) gained from BUTTE, SUTTER, and YOLO. (Calif. Stats. 1856, 7th sess., ch. 105/p. 124)
19 Feb 1857 COLUSI (now COLUSA) gained from TEHAMA. (Calif. Stats. 1857, 8th sess., ch. 37/p. 25)
by Jan 1859 By January 1859, the spelling of "COLUSI" changed to "COLUSA." (Calif. Stats. 1859, 10th sess.; [Green], 44–45)
19 Apr 1859 COLUSA lost to TEHAMA. (Calif. Stats. 1859, 10th sess., ch. 322/p. 359)
24 Mar 1868 COLUSA lost to LAKE. (Calif. Stats. 1867, 17th sess., ch. 257/p. 269)
01 Jan 1873 COLUSA gained from TEHAMA, lost to BUTTE. (Political Code 1872, 1: secs. 3915–3916, 3922/pp. 118–119, 123–124)
31 Mar 1891 COLUSA lost small area to SUTTER [for location see 1891_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1891, 29th sess., ch. 240/p. 455)
05 May 1891 COLUSA lost to creation of GLENN. Act passed 11 March 1891; referendum for or against creation of the new county held 5 May 1891. (Calif. Stats. 1891, 29th sess., ch. 94/pp. 98–101)
11 Mar 1893 COLUSA gained from GLENN. (Calif. Stats. 1893, 30th sess., ch. 141/p. 158)
13 Mar 1909 Boundary of LAKE with COLUSA and MENDOCINO redefined [no change]. (Calif. Stats. 1909, 38th sess., ch. 211/pp. 326–328)
COLUSI (see COLUSA)
18 Feb 1850 CONTRA COSTA created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 10/p. 60)
05 Apr 1850 CONTRA COSTA boundaries clarified [no change]. (Calif. Stats. 1849, 1st sess., ch. 61, sec. 4/p. 156)
25 Apr 1851 CONTRA COSTA boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 10/p. 174)
14 Feb 1852 CONTRA COSTA lost to SAN JOAQUIN. (Calif. Stats. 1852, 3d sess., chs. 105–106/pp. 178–180; Purcell, 250)
25 Mar 1853 CONTRA COSTA lost to creation of ALAMEDA, and lost small remnant to SANTA CLARA. (Calif. Stats. 1853, 4th sess., ch. 41/pp. 56–59)
26 Mar 1868 CONTRA COSTA gained the Brothers Islands from MARIN. (Calif. Stats. 1867, 17th sess., ch. 305/p. 347)
14 Jan 1958 CONTRA COSTA lost small area to ALAMEDA [for location see 1958_pt.shp; change too small to display on interactive map]. (Coy, 338–339)
01 Sep 1992 CONTRA COSTA lost small area to ALAMEDA. Ordinance passed 11 August 1992; effective 1 September 1992 [for location see 1992_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Alameda County, 11 August 1992, ordinance 92–57)
04 Oct 1995 CONTRA COSTA gained small area from ALAMEDA [for location see 1995_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1995, reg. sess., ch. 529, sec. 3 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002)
04 Apr 1864 Legislature authorized creation of COSO from MONO and TULARE; creation did not take effect [see creation of INYO, 22 March 1866]. (Calif. Stats. 1863–1864, 15th sess., ch. 470/pp. 528–530)
02 Mar 1857 DEL NORTE created from KLAMATH (extinct) and a small area of SISKIYOU. (Calif. Stats. 1857, 8th sess., ch. 52/pp. 35–36)
11 Feb 1858 DEL NORTE boundaries clarified [no change]. (Calif. Stats. 1858, 9th sess., ch. 23/p. 21)
01 Jan 1873 DEL NORTE exchanged with SISKIYOU. (Political Code 1872, 1: secs. 3909–3910, 3913/pp. 113–115, 117)
11 Mar 1887 DEL NORTE exchanged with SISKIYOU. (Calif. Stats. 1887, 27th sess., ch. 88/pp. 105–107)
23 Mar 1901 DEL NORTE exchanged with HUMBOLDT. (Calif. Stats. 1901, 34th sess., ch. 193/p. 600)
18 Feb 1850 Area between BRANCIFORTE (now SANTA CRUZ) and SAN FRANCISCO was in dispute. Both counties claimed the area. (Calif. Stats. 1849, 1st sess., ch. 15, secs. 7–8/pp. 59–60; Stanger, 88)
01 Jul 1856 SAN MATEO created from SAN FRANCISCO; SAN MATEO boundary with SANTA CRUZ was in dispute [see 18 February 1850]. Dispute ended 18 April 1857 when SAN MATEO gained control over the area. (Calif. Stats. 1856, 7th sess., ch. 125/pp. 145–146, 176–178)
18 Feb 1850 EL DORADO created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 18/pp. 61–62)
25 Apr 1851 EL DORADO boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 16/p. 176)
16 Apr 1855 EL DORADO lost to AMADOR. (Calif. Stats. 1855, 6th sess., ch. 92/p. 113)
25 Apr 1857 EL DORADO exchanged with AMADOR. (Calif. Stats. 1857, 8th sess., ch. 220/p. 251)
08 Apr 1863 EL DORADO lost to AMADOR. (Calif. Stats. 1863, 14th sess., ch. 170/p. 231)
20 Apr 1863 EL DORADO gained from PLACER. (Calif. Stats. 1863, 14th sess., ch. 263/p. 349)
16 Mar 1864 EL DORADO lost to creation of ALPINE. (Calif. Stats. 1863–1864, 15th sess., ch. 180/pp. 178–182)
10 Aug 1913 EL DORADO exchanged with PLACER. (Calif. Stats. 1913, 40th sess., chs. 315–316/pp. 603–605)
30 Jun 1991 EL DORADO lost small area to AMADOR. Ordinance passed 25 June 1991; effective 30 June 1991 [for location see 1991_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, El Dorado County, 25 June 1991, resolution 211–91; Minutes of the Board of Supervisors, Amador County, 12 June 1990, resolution 90–182)
19 Apr 1856 FREZNO (now FRESNO) created from CALAVERAS, MARIPOSA, MERCED, TULARE, and TUOLUMNE. (Calif. Stats. 1856, 7th sess., ch. 127/pp. 183)
11 Apr 1859 FREZNO (now FRESNO) lost to TUOLUMNE. (Calif. Stats. 1859, 10th sess., ch. 204/p. 213)
24 Apr 1861 FREZNO (now FRESNO) lost to creation of MONO. (Calif. Stats. 1861, 12th sess., ch. 233/pp. 235–236)
by Apr 1862 By April 1862, the phonetic spelling of "FREZNO" changed to "FRESNO." (Calif. Stats. 1863, 13th sess.; Gudde, 138)
29 Mar 1870 FRESNO lost to MARIPOSA. (Calif. Stats. 1869, 18th sess., ch. 341/p. 449)
01 Apr 1872 FRESNO gained from MARIPOSA. (Calif. Stats. 1871, 19th sess., ch. 602/p. 891)
11 Feb 1874 Boundary between FRESNO and MARIPOSA redefined [no change]. (Calif. Stats. 1873, 20th sess., ch. 88/p. 100)
27 Mar 1874 FRESNO exchanged with TULARE. (Calif. Stats. 1873, 20th sess., ch. 468/p. 700)
23 Mar 1876 FRESNO exchanged with TULARE. (Calif. Stats. 1875, 21st sess., ch. 301/p. 397)
11 Mar 1887 FRESNO lost to SAN BENITO. (Calif. Stats. 1887, 27th sess., ch. 86/p.103)
16 May 1893 FRESNO lost to creation of MADERA. Act passed 11 March 1893; referendum for or against creation of new county held 16 May 1893. (Calif. Stats. 1893, 30th sess., ch. 143/pp. 168–172; California USGenWeb Project, Madera County, http://www.cagenweb.com/madera/MadHistory.html, 17 July 2002; "Mariposa County v. Madera County," in Calif. Rpts., 142:50–58)
14 Mar 1907 Legislature authorized KINGS to gain from FRESNO, dependent on local referendum. Referendum failed [no change]. [Proposed change not displayed on interactive map; see "Special Topics."] (Calif. Stats. 1907, 37th sess., ch. 214/pp. 260–263; Coy, 51–52; "Wheeler v. Herbert," in Calif. Rpts., 152:224–241)
12 Apr 1909 FRESNO lost to KINGS. (Calif. Stats. 1909, 38th sess., ch. 483/pp. 827–829)
31 Dec 1986 FRESNO gained small area from TULARE. Ordinance passed 18 November 1986; effective 31 December 1986 [for location see 1986_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Tulare County, 18 November 1986, ordinance 2745)
30 Sep 1991 FRESNO exchanged small areas with TULARE. Ordinance passed 3 September 1991; effective 30 September 1991 [for location see 1991_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Tulare County, 3 September 1991, ordinance 2970)
FREZNO (see FRESNO)
05 May 1891 GLENN created from COLUSA. Act passed 11 March 1891; referendum for or against creation of the new county held 5 May 1891. (Calif. Stats. 1891, 29th sess., ch. 94/pp. 98–101)
11 Mar 1893 GLENN lost to COLUSA. (Calif. Stats. 1893, 30th sess., ch. 141/p. 158)
08 Mar 1907 GLENN gained from MENDOCINO. (Calif. Stats. 1907, 37th sess., ch. 113/p. 135)
13 Mar 1909 GLENN exchanged with LAKE. (Calif. Stats. 1909, 38th sess., ch. 211, sec. 2/p. 327)
08 Aug 1915 GLENN lost small area in section 3, township 19 north, range 1 east to BUTTE [for location see 1915_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1915, 41st sess., ch. 532/p. 898)
12 May 1853 HUMBOLDT created from TRINITY. (Calif. Stats. 1853, 4th sess., ch. 114/pp. 161–164)
11 Mar 1859 HUMBOLDT lost to MENDOCINO. (Calif. Stats. 1859, 10th sess., ch. 108/pp. 98–99)
28 Apr 1860 HUMBOLDT gained from MENDOCINO. (Calif. Stats. 1860, 11th sess., ch. 340/p. 334)
11 Feb 1862 HUMBOLDT boundaries redefined [no change]. (Calif Laws 1862, 13th sess., ch. 11/p. 6)
30 May 1874 HUMBOLDT gained part of KLAMATH; KLAMATH eliminated. Act passed 28 March 1874; referendum for annexation of KLAMATH held 30 May 1874. (Calif. Stats. 1873, 20th sess., ch. 520/pp. 755–758; Kasch, 270–272)
23 Mar 1901 HUMBOLDT exchanged with DEL NORTE, lost small area to SISKIYOU. (Calif. Stats. 1901, 34th sess., ch. 193/p. 600)
12 Aug 1907 IMPERIAL created from SAN DIEGO. (Coy, 50–51; Farr, 18–19)
16 Jun 1967 IMPERIAL boundaries redefined to more precisely define the boundary between IMPERIAL and the State of Arizona [no discernible change]. (Calif. Stats. 1967, reg. sess., ch. 339/pp. 1536–1537; Coy, 339)
22 Mar 1866 INYO created from MONO and TULARE. INYO boundaries were identical to those of COSO (proposed) [see 4 April 1864]. (Calif. Stats. 1865, 16th sess., ch. 316/pp. 355–358)
28 Mar 1870 INYO gained from MONO. (Calif. Stats. 1869, 18th sess., ch. 323/p. 421)
01 Jan 1873 INYO gained from KERN and SAN BERNARDINO. (Political Code 1872, 1: secs. 3941–3943/pp. 139–140)
19 Sep 1947 Boundary between INYO and SAN BERNARDINO placed in dispute. Section 23136 of Political Code was revised to authorize SAN BERNARDINO to gain from INYO a strip of territory one and one-half miles wide between the San Bernardino Meridian and the state line. The companion description of INYO boundaries in section 23114 authorized no such change [no change]. (Calif. Stats. 1947, reg. sess., ch. 424, secs. 23114, 23136/pp. 1050, 1068)
11 Sep 1957 INYO lost small area to SAN BERNARDINO; boundaries of INYO and SAN BERNARDINO clarified, ending boundary dispute dating from 1947. (Calif. Stats. 1957, reg. sess., ch. 2382/p. 4119)
1972 In 1972, boundary between INYO and SAN BERNARDINO was adjusted [precise location unknown, not mapped]. (Correspondence, California State Board of Equalization, 25 July 2002)
02 Apr 1866 KERN created from LOS ANGELES and TULARE. (Calif. Stats. 1865, 16th sess., ch. 569/pp. 796–798)
10 Feb 1868 KERN gained from TULARE. (Calif. Stats. 1867, 17th sess., ch. 43/p. 40)
01 Jan 1873 KERN lost to INYO and TULARE. Boundary with VENTURA adjusted to run partially on public land survey lines. (Political Code 1872, 1: secs. 3940–3942/pp. 138–139)
14 Mar 1885 KERN exchanged with SAN LUIS OBISPO. (Calif. Stats. 1885, 26th sess., ch. 149/pp. 139–141)
27 Jul 1917 KERN lost to SAN BERNARDINO. (Calif. Stats. 1917, 42d sess., ch. 205/p. 301)
23 Jul 1919 KERN gained from VENTURA when boundary was adjusted to run on public land survey lines. The California Supreme Court declared this chapter unconstitutional on 19 February 1920, but this particular change appears to have remained in effect; change confirmed in 1923 by reenactment of the 1919 law. (Calif. Stats. 1919, 43d sess., ch. 470, secs. 3923, 3964/pp. 870, 908–909; "Mundell v. Lyons," in Calif. Rpts., 182:289–293; Calif. Laws 1923, 45th sess., ch. 160, secs. 16, 57/pp. 336, 373)
16 May 1923 KERN boundaries redefined; see 23 July 1919 [no change]. (Calif. Laws 1923, 45th sess., ch. 160, secs. 16, 57/pp. 336, 373)
13 May 1963 KERN exchanged small areas with SAN BERNARDINO. (Coy, 340, 342; correspondence, California Board of Equalization, 25 July 2002)
31 Dec 1986 KERN gained small area from VENTURA [precise location unknown, not mapped]. (Minutes of the Board of Supervisors, Kern County, 4 November 1986, ordinance G–4345)
10 Jun 1991 KERN gained from VENTURA. (Calif. Stats. 1991–1992, reg. sess., ch. 51/p. 150)
23 May 1893 KINGS created from TULARE. Act passed 22 March 1893; referendum for or against creation of new county held 23 May 1893. (Calif. Stats. 1893, 30th sess., ch. 150/pp. 176–181; Kings County History, http://calflytech.com/kingshistory.html, 18 July 2002)
14 Mar 1907 Legislature authorized KINGS to gain from FRESNO, dependent on local referendum. Referendum failed [no change]. [Proposed change not displayed on interactive map; see "Special Topics."] (Calif. Stats. 1907, 37th sess., ch. 214/pp. 260–263; Coy, 51–52; "Wheeler v. Herbert," in Calif. Rpts., 152:224–241)
12 Apr 1909 KINGS gained from FRESNO. (Calif. Stats. 1909, 38th sess., ch. 483/pp. 827–829)
25 Apr 1851 KLAMATH (extinct) created from TRINITY. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 31/p. 180)
22 Mar 1852 KLAMATH (extinct) lost to creation of SISKIYOU. (Calif. Stats. 1852, 3d sess., ch. 146/pp. 233–235)
30 Apr 1855 KLAMATH (extinct) lost to TRINITY. (Calif. Stats. 1855, 6th sess., ch. 156/p. 200)
02 Mar 1857 KLAMATH (extinct) lost to creation of DEL NORTE. (Calif. Stats. 1857, 8th sess., ch. 52/pp. 35–36)
30 May 1874 KLAMATH lost all territory to HUMBOLDT and SISKIYOU; KLAMATH eliminated. Act passed 28 March 1874; referendum for annexation of KLAMATH held 30 May 1874. (Calif. Stats. 1873, 20th sess., ch. 520/pp. 755–758; Kasch, 270–272)
20 May 1861 LAKE created from NAPA. (Calif. Stats. 1861, 12th sess., ch. 498/pp. 560–561)
29 Feb 1864 LAKE gained from MENDOCINO and NAPA. (Calif. Stats. 1863–1864, 15th sess., ch. 122/p. 111)
24 Mar 1868 LAKE gained from COLUSA, NAPA, and YOLO. (Calif. Stats. 1867, 17th sess., ch. 257/p. 269)
08 Mar 1872 LAKE lost to NAPA. (Calif. Stats. 1871, 19th sess., ch. 229/p. 305)
08 Mar 1907 LAKE lost to MENDOCINO. (Calif. Stats. 1907, 37th sess., ch. 113/p. 135)
13 Mar 1909 LAKE exchanged with GLENN; boundary of LAKE with COLUSA and MENDOCINO redefined [no change]. (Calif. Stats. 1909, 38th sess., ch. 211/pp. 326–328)
31 Jul 1917 LAKE exchanged with MENDOCINO. (Calif. Stats. 1917, 42d sess., ch. 779/pp. 1635–1640)
01 Apr 1864 LASSEN created from PLUMAS and SHASTA. (Calif. Stats. 1863–1864, 15th sess., ch. 261/pp. 264–269)
26 Mar 1866 LASSEN boundaries clarified [no change]. (Calif. Stats. 1865, 16th sess., ch. 371/p. 453)
01 Jan 1873 LASSEN gained from PLUMAS. (Political Code 1872, 1: secs. 3912, 3920/pp. 115–116, 122–123)
16 Mar 1874 LASSEN lost small area to SIERRA when boundary was set on public land survey lines. (Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, p. 166)
14 Mar 1899 LASSEN gained from SHASTA. (Calif. Stats. 1899, 33d sess., ch. 82/p. 98)
28 Feb 1901 LASSEN exchanged with PLUMAS. (Calif. Stats. 1901, 34th sess., ch. 61/pp. 76–80)
18 Feb 1850 LOS ANGELES created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 3/p. 59)
25 Apr 1851 LOS ANGELES gained from MARIPOSA, exchanged with SAN DIEGO and SANTA BARBARA. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 3/p. 172)
26 Apr 1853 LOS ANGELES lost to creation of SAN BERNARDINO. (Calif. Stats. 1853, 4th sess., ch. 78/pp. 119–123)
26 Mar 1856 LOS ANGELES boundaries redefined [no change]. (Calif. Stats. 1856, 7th sess., ch. 46/p. 53)
02 Apr 1866 LOS ANGELES lost to creation of KERN. (Calif. Stats. 1865, 16th sess., ch. 569/pp. 796–798)
01 Jan 1873 LOS ANGELES lost to SAN DIEGO. (Political Code 1872, 1: secs. 3944–3945/pp. 140–142)
05 Feb 1877 LOS ANGELES lost to SAN BERNARDINO as a result of an official survey of the boundary. (Coy, 149, 217–219)
Jul 1881 In July 1881, LOS ANGELES lost to VENTURA as a result of an official boundary survey. (Coy, 150–154, 292)
04 Jun 1889 LOS ANGELES lost to creation of ORANGE. Act passed 11 March 1889; referendum for or against creation of new county held 4 June 1889. (Calif. Stats. 1889, 28th sess., ch. 110/pp. 123–129)
23 Jul 1919 The new Political Code authorized LOS ANGELES to exchange with VENTURA. This chapter of the 1919 revision of the laws did not take effect and was found unconstitutional by the California Supreme Court, 19 February 1920. [Proposed change not displayed on interactive map; see "Special Topics."] (Calif. Stats. 1919, 43d sess., ch. 470, secs. 3927, 3964/pp. 877–879, 908–909; "Mundell v. Lyons," in Calif. Rpts., 182:289–293; Coy, 152-153)
01 Sep 1987 LOS ANGELES lost small area in Cypress Memorial Park Cemetery to ORANGE. Ordinance passed 29 July 1987; effective 1 September 1987 [for location see 1987_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Orange County, 29 July 1987, ordinance 3647)
01 Mar 1992 LOS ANGELES lost small area to SAN BERNARDINO. Ordinance passed 27 January 1992; effective 1 March 1992 [for location see 1992_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, San Bernardino County, 27 January 1992, ordinance 3478)
11 Oct 1993 LOS ANGELES lost small area to SAN BERNARDINO [for location see 1993_pt.shp; change too small to display on interactive map]. (Calif. Stats. 1993–1994, reg. sess., ch. 1195, sec. 3/p. 6854)
30 Sep 1999 LOS ANGELES lost small area to ORANGE [for location see 1999_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Los Angeles County, 24 August 1999, ordinance 99–0077M)
19 Sep 2000 Boundary between LOS ANGELES and ORANGE redefined to incorporate 1999 boundary change [no change]. (Calif. Stats. 2000, reg. sess., ch. 506, secs. 15–16 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002)
16 May 1893 MADERA created from FRESNO. Act passed 11 March 1893; referendum for or against creation of new county held 16 May 1893. (Calif. Stats. 1893, 30th sess., ch. 143/pp. 168–172; California USGenWeb Project, Madera County, http://www.cagenweb.com/madera/MadHistory.html, 17 July 2002; "Mariposa County v. Madera County," in Calif. Rpts., 142:50–58)
03 May 1852 Mare Island was inadvertently left outside the jurisdiction of any county when SONOMA boundaries were redefined. It remained a non-county area until it became part of SOLANO on 27 January 1853. (Calif. Stats. 1852, 3d sess., ch. 147/p. 236)
18 Feb 1850 MARIN created from non-county area; MARIN not fully organized, attached to SONOMA "for judicial purposes." (Calif. Stats. 1849, 1st sess., ch. 15, sec. 11/p. 60)
22 Apr 1850 MARIN fully organized, detached from SONOMA. (Calif. Stats. 1849, 1st sess., ch. 131/p. 406)
25 Apr 1851 MARIN boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 23/pp. 177–178)
15 May 1854 MARIN gained "Island of Los Angeles" (Angel Island) in San Francisco Bay from SAN FRANCISCO. (Calif. Stats. 1854, 5th sess., ch. 67/p. 121)
27 Apr 1855 MARIN lost to SONOMA. (Calif. Stats. 1855, 6th sess., ch. 125/p. 150)
18 Apr 1857 MARIN lost Angel Island in San Francisco Bay to SAN FRANCISCO. (Calif. Stats. 1857, 8th sess., ch. 190/pp. 209–210)
25 Apr 1860 MARIN gained from SONOMA when boundary was changed to run on road [see 13 May 1861]; MARIN gained Angel Island in San Francisco Bay from SAN FRANCISCO. (Calif. Stats. 1860, 11th sess., ch. 288/p. 269)
13 May 1861 MARIN lost to SONOMA [repealed part of act of 25 April 1860]. (Calif. Stats. 1861, 12th sess., ch. 346/p. 351)
26 Mar 1868 MARIN lost the Brothers Islands to CONTRA COSTA. (Calif. Stats. 1867, 17th sess., ch. 305/p. 347)
18 Feb 1850 MARIPOSA created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 28/p. 63)
25 Apr 1851 MARIPOSA gained from SAN DIEGO, lost to LOS ANGELES. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 15/pp. 175–176)
20 Apr 1852 MARIPOSA lost to creation of TULARE. (Calif. Stats. 1852, 3d sess., ch. 153/pp. 240–242)
19 Apr 1855 MARIPOSA lost to creation of MERCED. (Calif. Stats. 1855, 6th sess., ch. 104/pp. 125–128)
19 Apr 1856 MARIPOSA lost to creation of FREZNO (now FRESNO). (Calif. Stats. 1856, 7th sess., ch. 127/pp. 183)
24 Apr 1861 MARIPOSA lost a remnant of territory to creation of MONO. (Calif. Stats. 1861, 12th sess., ch. 233/pp. 235–236)
29 Mar 1870 MARIPOSA gained from FRESNO. (Calif. Stats. 1869, 18th sess., ch. 341/p. 449)
01 Apr 1872 MARIPOSA lost to FRESNO. (Calif. Stats. 1871, 19th sess., ch. 602/p. 891)
11 Feb 1874 Boundary between MARIPOSA and FRESNO redefined [no change]. (Calif. Stats. 1873, 20th sess., ch. 88/p. 100)
18 Feb 1850 MENDOCINO created from non-county area; MENDOCINO not fully organized, attached to SONOMA "for judicial purposes." (Calif. Stats. 1849, 1st sess., ch. 15, sec. 16/p. 61)
25 Apr 1851 MENDOCINO boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 26/pp. 178–179)
16 Apr 1852 MENDOCINO lost to NAPA. (Calif. Stats. 1852, 3d sess., ch. 116/p. 192)
04 Apr 1855 MENDOCINO lost to NAPA. (Calif. Stats. 1855, 6th sess., ch. 68/p. 77)
27 Apr 1855 MENDOCINO exchanged with SONOMA. (Calif. Stats. 1855, 6th sess., ch. 125/p. 150)
11 Mar 1859 MENDOCINO gained from HUMBOLDT and TRINITY, exchanged with SONOMA. (Calif. Stats. 1859, 10th sess., ch. 108/pp. 98–99)
02 May 1859 MENDOCINO fully organized, detached from SONOMA. (Calif. Stats. 1859, 10th sess., ch. 108, sec. 2/p. 99; History of Mendocino County, 272–273, 283)
28 Apr 1860 MENDOCINO lost to HUMBOLDT and TRINITY. (Calif. Stats. 1860, 11th sess., ch. 340/p. 334)
29 Feb 1864 MENDOCINO lost to LAKE. (Calif. Stats. 1863–1864, 15th sess., ch. 122/p. 111)
30 Oct 1872 MENDOCINO lost to TRINITY when their common boundary was surveyed; later MENDOCINO claimed a different boundary based on an 1891 survey. California Supreme Court upheld 1872 survey on 15 May 1907. (Calif. Stats. 1871, 19th sess., ch. 531/p. 766; "Trinity County v. Mendocino County," in Calif. Rpts., 151: 279–289)
08 Mar 1907 MENDOCINO gained from LAKE, lost to GLENN. (Calif. Stats. 1907, 37th sess., ch. 113/p. 135)
13 Mar 1909 Boundary of LAKE with MENDOCINO and COLUSA redefined [no change]. (Calif. Stats. 1909, 38th sess., ch. 211/pp. 326–328)
30 Jul 1917 MENDOCINO exchanged with SONOMA. (Calif. Stats. 1917, 42d sess., ch. 725/p. 1396)
31 Jul 1917 MENDOCINO exchanged with LAKE. (Calif. Stats. 1917, 42d sess., ch. 779/pp. 1635–1640)
19 Apr 1855 MERCED created from MARIPOSA. (Calif. Stats. 1855, 6th sess., ch. 104/pp. 125–128)
19 Apr 1856 MERCED lost to creation of FREZNO (now FRESNO) and lost to TULARE. (Calif. Stats. 1856, 7th sess., ch. 127/pp. 183)
08 Mar 1866 Legislature authorized a re-survey of the MERCED-STANISLAUS line, established in 1854, which would have resulted in MERCED gaining from STANISLAUS. Gain did not take effect; see 13 February 1868. [Proposed change not displayed on interactive map; see "Special Topics."] (Calif. Stats. 1865, 16th sess., ch. 191/p. 172; Outcalt, 118–119, 122–123)
13 Feb 1868 Boundary between MERCED and STANISLAUS redefined to confirm 1854 STANISLAUS line; see 8 March 1866 [no change]. (Calif. Stats. 1867, 17th sess., ch. 57/p. 56)
11 Mar 1887 MERCED lost small area to SAN BENITO. (Calif. Stats. 1887, 27th sess., ch. 86/p.103)
17 Feb 1874 MODOC created from SISKIYOU. (Calif. Stats. 1873, 20th sess., ch. 107/pp. 124–129)
24 Apr 1861 MONO created from CALAVERAS, FREZNO (now FRESNO), and remnant of MARIPOSA. Due to uncertainty about the precise location of the boundary between California and Nevada Territory, the county seat of MONO, Aurora, was actually located in Nevada. (Calif. Stats. 1861, 12th sess., ch. 233/pp. 235–236; Chappell, 239–242; "Reddy v. Tinkum," in Calif. Rpts., 60:458–467)
16 Mar 1864 MONO lost to creation of ALPINE. (Calif. Stats. 1863–1864, 15th sess., ch. 180/pp. 178–182)
04 Apr 1864 Legislature authorized creation of COSO from MONO and TULARE; creation did not take effect [see creation of INYO, 22 March 1866]. (Calif. Stats. 1863–1864, 15th sess., ch. 470/pp. 528–530)
02 Mar 1866 MONO gained remnant of AMADOR that was left separate from the rest of AMADOR after the creation of ALPINE. (Calif. Stats. 1865, 16th sess., ch. 161/p. 144)
22 Mar 1866 MONO lost to creation of INYO; INYO boundaries were identical to those of COSO (proposed) [see 4 April 1864]. (Calif. Stats. 1865, 16th sess., ch. 316/pp. 355–358)
22 Jan 1870 MONO gained from TULARE the remnant of territory that was separated from TULARE by the creation of INYO on 22 March 1866. (Calif. Stats. 1869, 18th sess., ch. 18/p. 20)
28 Mar 1870 MONO lost to INYO. (Calif. Stats. 1869, 18th sess., ch. 323/p. 421)
18 Feb 1850 MONTEREY created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 6/p. 59)
25 Apr 1851 MONTEREY exchanged with SAN LUIS OBISPO. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 6/p. 173)
13 May 1861 MONTEREY lost to SAN LUIS OBISPO. (Calif. Stats. 1861, 12th sess., ch. 342/p. 349)
20 Apr 1863 MONTEREY gained from SAN LUIS OBISPO. (Calif. Stats. 1863, 14th sess., ch. 276/p. 358)
12 Feb 1874 MONTEREY lost to creation of SAN BENITO. (Calif. Stats. 1873, 20th sess., ch. 87/pp. 95–99)
18 Feb 1850 NAPA created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 15/p. 61)
25 Apr 1851 NAPA boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 25/p. 178)
16 Apr 1852 NAPA gained from MENDOCINO. (Calif. Stats. 1852, 3d sess., ch. 116/p. 192)
04 Apr 1855 NAPA gained from MENDOCINO, SOLANO, and SONOMA. (Calif. Stats. 1855, 6th sess., ch. 68/p. 77)
20 May 1861 NAPA lost to creation of LAKE. (Calif. Stats. 1861, 12th sess., ch. 498/pp. 560–561)
29 Feb 1864 NAPA lost to LAKE. (Calif. Stats. 1863–1864, 15th sess., ch. 122/p. 111)
24 Mar 1868 NAPA lost small area to LAKE. (Calif. Stats. 1867, 17th sess., ch. 257/p. 269)
08 Mar 1872 NAPA gained from LAKE. (Calif. Stats. 1871, 19th sess., ch. 229/p. 305)
25 Apr 1851 NEVADA created from YUBA. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 20/p. 177)
03 May 1852 NEVADA gained from SIERRA. (Calif. Stats. 1852, 3d sess., chs. 114–115/pp. 190–192)
19 Apr 1856 NEVADA gained from SIERRA. (Calif. Stats. 1856, 7th sess., ch. 122/p. 143)
28 Dec 1908 California Supreme Court settled boundary dispute between NEVADA and SIERRA in favor of SIERRA. Dispute grew out of disagreement over the location of the source of the South Fork of Middle Yuba River [no change]. ("Sierra County v. Nevada County," in Calif. Rpts., 155:1–15)
01 Mar 1909 NEVADA boundary with SIERRA clarified to run on public land survey lines [no discernible change]. (Calif. Stats. 1909, 38th sess., ch. 75, sec. 2/p. 86)
04 Jun 1889 ORANGE created from LOS ANGELES. Act passed 11 March 1889; referendum for or against creation of new county held 4 June 1889. (Calif. Stats. 1889, 28th sess., ch. 110/pp. 123–129)
01 Sep 1987 ORANGE gained small area in Cypress Memorial Park Cemetery from LOS ANGELES. Ordinance passed 29 July 1987; effective 1 September 1987 [for location see 1987_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Orange County, 29 July 1987, ordinance 3647)
08 Nov 1988 ORANGE exchanged small areas with RIVERSIDE. Ordinance passed 27 September 1988; effective 8 November 1988. (Minutes of the Board of Supervisors, Riverside County, 27 September 1988, ordinance 665)
01 Jul 1992 Boundary between ORANGE and RIVERSIDE restated [no change]. Ordinance passed 26 November 1991; effective 1 July 1992. (Minutes of the Board of Supervisors, Riverside County, 26 November 1991, ordinance 717)
11 Oct 1993 ORANGE boundaries redefined [no change]. (Calif. Stats. 1993–1994, reg. sess., ch. 1195, sec. 4/pp. 6855–6858)
30 Sep 1999 ORANGE gained small area from LOS ANGELES [for location see 1999_pt.shp; change too small to display on interactive map]. (Minutes of the Board of Supervisors, Los Angeles County, 24 August 1999, ordinance 99–0077M)
19 Sep 2000 Boundary between ORANGE and LOS ANGELES redefined to incorporate 1999 boundary change [no change]. (Calif. Stats. 2000, reg. sess., ch. 506, secs. 15–16 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002)
03 May 1852 California Legislature proposed creation of PAUTAH in Utah Territory (present Nevada). Creation never took effect because the United States never ceded the area to California. (Calif. Stats. 1852, 3d sess., ch. 118/p. 193; "Historical and Political Data, Carson County, Utah Territory," Political History of Nevada 1996, http://dmla.clan.lib.nv.us/docs/nsla/archives/political/historical/hist05.htm, 12 December 2002)
08 Apr 1859 PAUTAH legally eliminated; ended the attempt by California to gain part of Utah Territory (present Nevada). (Calif. Stats. 1859, 10th sess., ch. 183/p. 186)
25 Apr 1851 PLACER created from SUTTER and YUBA. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 17/p. 176)
20 Apr 1863 PLACER lost to EL DORADO. (Calif. Stats. 1863, 14th sess., ch. 263/p. 349)
13 Mar 1866 PLACER exchanged with SUTTER. (Calif. Stats. 1865, 16th sess., ch. 224/p. 223)
01 Jan 1873 PLACER gained small area from SUTTER. (Political Code 1872, 1: sec. 3924, 3926/pp. 125–127)
19 Mar 1889 PLACER boundaries clarified [no change]. (Calif. Stats. 1889, 28th sess., ch. 262/p. 402)
10 Aug 1913 PLACER exchanged with EL DORADO. (Calif. Stats. 1913, 40th sess., chs. 315–316/pp. 603–605)
01 Apr 1854 PLUMAS created from BUTTE. (Calif. Stats. 1854, 5th sess., ch. 1/pp. 129–131)
27 Mar 1863 PLUMAS lost to SIERRA. (Calif. Stats. 1863, 14th sess., ch. 101/p. 114; Sinnott, 6:19–22)
01 Apr 1864 PLUMAS lost to creation of LASSEN. (Calif. Stats. 1863–1864, 15th sess., ch. 261/pp. 264–269)
31 Mar 1866 PLUMAS gained from SIERRA and gained small area from YUBA. (Calif. Stats. 1865, 16th sess., ch. 466/p. 605)
28 Mar 1868 PLUMAS lost small area to SIERRA. (Calif. Stats. 1867, 17th sess., ch. 377/p. 462)
01 Jan 1873 PLUMAS lost to LASSEN and SHASTA. (Political Code 1872, 1: secs. 3911–3912, 3920/pp. 115–116, 122–123)
16 Mar 1874 PLUMAS lost small area to SIERRA when boundary was set on public land survey lines. (Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, p. 166)
28 Feb 1901 PLUMAS exchanged with LASSEN. (Calif. Stats. 1901, 34th sess., ch. 61/pp. 76–80)
23 Mar 1901 PLUMAS exchanged with BUTTE; boundary between PLUMAS and SHASTA clarified to run on public land survey line [no discernible change]. (Calif. Stats. 1901, 34th sess., chs. 146, 171/pp. 549–551, 560)
02 May 1893 RIVERSIDE created from SAN BERNARDINO and SAN DIEGO. Act passed 11 March 1893; referendum for or against creation of new county held 2 May 1893. (Calif. Stats. 1893, 30th sess., ch. 142/pp. 158–168)
22 Jul 1919 RIVERSIDE exchanged with SAN BERNARDINO. (Calif. Stats. 1919, 43d sess., ch. 62/p. 99)
16 Jun 1967 RIVERSIDE boundaries redefined to more precisely define the boundary between RIVERSIDE and the State of Arizona [no discernible change]. (Calif. Stats. 1967, reg. sess., ch. 340/pp. 1537–1539; Coy, 340)
08 Nov 1988 RIVERSIDE exchanged small areas with ORANGE. Ordinance passed 27 September 1988; effective 8 November 1988. (Minutes of the Board of Supervisors, Riverside County, 27 September 1988, ordinance 665)
01 Jul 1992 Boundary between RIVERSIDE and ORANGE restated [no change]. Ordinance passed 26 November 1991; effective 1 July 1992. (Minutes of the Board of Supervisors, Riverside County, 26 November 1991, ordinance 717)
11 Oct 1993 RIVERSIDE boundaries redefined [no change]. (Calif. Stats. 1993–1994, reg. sess., ch. 1195, sec. 5/pp. 6858–6860)
18 Feb 1850 SACRAMENTO created from non-county area. (Calif. Stats. 1849, 1st sess., ch. 15, sec. 17/p. 61; Tinkham, 64)
25 Apr 1851 SACRAMENTO boundaries redefined [no change]. (Calif. Stats. 1851, 2d sess., ch. 14, sec. 11/p. 174)
30 Mar 1857 SACRAMENTO boundaries redefined [no change]. (Calif. Stats. 1857, 8th sess., ch. 120/p. 132)
23 Apr 1861 SACRAMENTO gained from SAN JOAQUIN. (Calif. Stats. 1861, 12th sess., ch. 219/p. 221; Tinkham, 64–65)
13 Mar 1866 SACRAMENTO boundaries redefined [no change]. (Calif. Stats. 1865, 16th sess., ch. 224/p. 223)
12 Mar 1870 SACRAMENTO gained small areas from SOLANO and YOLO. (Calif. Stats. 1869, 18th sess., ch. 191/p. 294)
01 Apr 1878 SACRAMENTO lost to SAN JOAQUIN. (Calif. Stats. 1877, 22d sess., Acts Amendatory of the Political Code, ch. 636/p. 70)
18 Mar 1905 Boundary between SACRAMENTO and SAN JOAQUIN redefined [no change]. (Calif. Stats. 1905, 36th sess., ch. 167/p. 164)
14 Jul 1988 SACRAMENTO boundaries redefined [no change]. (Calif. Stats. 1987–1988, reg. sess., ch. 363/p. 1676)
12 Feb 1874 SAN BENITO created from MONTEREY. (Calif. Stats. 1873, 20th sess., ch. 87/pp. 95–99)
11 Mar 1887 SAN BENITO gained from FRESNO and gained small area from MERCED. (Calif. Stats. 1887, 27th sess., ch. 86/p.103)
26 Apr 1853 SAN BERNARDINO created from LOS ANGELES. (Calif. Stats. 1853, 4th sess., ch. 78/pp. 119–123)
02 Apr 1857 SAN BERNARDINO boundaries redefined [no change]. (Calif. Stats. 1857, 8th sess., ch. 142/p. 165)
01 Jan 1873 SAN BERNARDINO gained from SAN DIEGO, lost to INYO. (Political Code 1872, 1: secs. 3942–3944/pp. 139–141)
05 Feb 1877 SAN BERNARDINO gained from LOS ANGELES as a result of an official survey of the boundary. (Coy, 149, 217–219)
02 May 1893 SAN BERNARDINO lost to creation of RIVERSIDE. Act passed 11 March 1893; referendum for or against creation of new county held 2 May 1893. (Calif. Stats. 1893, 30th sess., ch. 142/pp. 158–168)
27 Jul 1917 SAN BERNARDINO gained from KERN. (Calif. Stats. 1917, 42d sess., ch. 205/p. 301)
22 Jul 1919 SAN BERNARDINO exchanged with RIVERSIDE. (Calif. Stats. 1919, 43d sess., ch. 62/p. 99)
19 Sep 1947 Boundary between SAN BERNARDINO and INYO placed in dispute. Section 23136 of Political Code was revised to authorize SAN BERNARDINO to gain from INYO a strip of territory one and one-half miles wide between the San Bernardino Meridian and the state line. The companion description of INYO boundaries in section 23114 authorized no such change [no change]. (Calif. Stats. 1947, reg. sess., ch. 424, secs. 23114, 23136/pp. 1050, 1068)
11 Sep 1957 SAN BERNARDINO gained small area from INYO; boundaries of SAN BERNARDINO and INYO clarified, ending boundary dispute dating from 1947. (Calif. Stats. 1957, reg. sess., ch. 2382/p. 4119)