1850: Shortly after the first counties in California were created. Sierra County does not yet exist. Most of its territory is part of Yuba County.


April 16, 1852: Sierra County is created. Thanks to massive gold deposits, Sierra County was teaming with people. During the mid 1850s, Downieville had grown to be the second largest city in California (San Francisco was larger). Downieville missed becoming the state capital by just one vote. Another reason for its creation was its great distance from the Yuba County seat of Marysville.

Calif. Stats. 1852, 3d sess., ch. 145/pp. 230–231.


May 3, 1852: The following month a southern strip of Sierra County was added to Nevada County.

Calif. Stats. 1852, 3d sess., chs. 114–115/pp. 190–192.


April 19, 1856: Sierra County lost another chunk of itself to Nevada.

Calif. Stats. 1856, 7th sess., ch. 122/p. 143.


March 27, 1863: Sierra County acquired a strip of land from Plumas County.

Calif. Stats. 1863, 14th sess., ch. 101/p. 114; Sinnott, 6:19–22)


March 13, 1866: Sierra County acquired a small chunk from Yuba Co.

Calif. Stats. 1865, 16th sess., ch. 229/p. 228.


March 31, 1866: Later in the same month, the La Porte area was ceded to Plumas County. For the prior three years, the people of La Porte area lobbied strongly to join Plumas County or to establish a new county. Included temporarily were mining towns in the mountains just south of La Porte.

Calif. Stats. 1865, 16th sess., ch. 466/p. 605.


March 27, 1868: The mountain mining towns south of Slate Creek were returned to Sierra Co. La Porte remained part of Plumas.

Calif. Stats. 1867, 17th sess., ch. 377/p. 462.

Later in 1868, uncertainty of the boundary near the source of the south fork of the Middle Yuba River let to a tax lawsuit against the Eureka company which occupied that land. A 1869 Supreme Court decision gave the small chunk of land to Sierra County.


March 16, 1874: Sierra County gained a small strip of land from Plumas and Lassen counties.

Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, p. 166.


Knowing the when and where of county boundary changes will suggest which counties you should be checking for local records. The early boundaries were based on surveys that were far from perfect. So most of the subsequent changes simply corrected errors or provided clarification.

For a precise and legal definition of the early boundary changes, go to Google Books and find the free ebook titled The General Laws of the State of California: from 1850 to 1864.

Please contact the Sierra County Coordinator if you have any questions, problems, corrections or new information regarding this website or its posted material. CAGenWeb Disclaimer.

COPYRIGHT 1996-2015 by Richard L Hanson (Sierra County Coordinator) on behalf of the California chapter of The USGenWeb Project. ALL RIGHTS RESERVED.

Site Updated: 26 June 2016


Another great reference is Illustrated History of PLUMAS, LASSEN & SIERRA Counties with CALIFORNIA form 1530 to 1850, Farriss & Smith, 1882, San Francisco. The Sierra County except can be found on RootsWeb.

The small maps appearing below document Sierra County’s many boundry changes. For the purpose of illustration, boundry changes are not to scale.

White line – contemporary county line.
Black line – historical county line
Yellow area – area of land added to or removed from the county.