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California County Formation years
1850 1851 1852 1853 1854 1855 1856 1857 1859 1860 1861 1863 1864 1866 1868
1870 1872 1874 1875 1876 1878 1881 1885 1887 1889 1891 1893 1897 1907 1909
1913 1917 1919 1925                      
California Map Abbreviations
unorg. = unorganized
g. = gained
w. = with
fr. = from
atmt. = attachment
exch = exchanged
nca.= non county area
ch. = changed

Ala - Alameda
Alp - Alpine
Am - Amador
But - Butte
Ca - Calaveras
CC - Contra Costa
Col - Colusa
Cos - Coso
Csi - Colusa
DN - Del Norte
ED - El Dorado
Fr - Fresno
Gl - Glenn
Hu - Humboldt
Im - Imperial
In - Inyo
Ke - Kern
Ki - Kings
Kl - Klamath
LA - Los Angeles
Lak - Lake
Las - Lassen
Mad - Madera
Men - Mendocino
Mer - Merced
Mno - Mono
Mnt - Monterey
Mod - Modoc
Mrn - Marin
Mrs - Mariposa
Na - Napa
Ne - Nevada
Or - Orange
Pa - Pautah
Pla - Placer
Plu - Plumas
Ri - Riverside
Sac - Sacramento
SBr - San Bernardino
SBt - San Benito
SCl - Santa Clara
Scr - Santa Cruz
SD - San Diego
SF - San Francisco
Sh - Shasta
Sie - Sierra
Sis - Siskiyou
SJ - San Joaquin
SLO - San Luis Obispo
SM - San Mateo
Sol - Solano
Son - Sonoma
St - Stanislaus
StB - Santa Barbara
Su - Sutter
Te - Tehama
Tr - Trinity
Tul - Tulare
Tuo - Tuolomne
Ve - Ventura
Yo - Yolo
Yu - Yuba