The original boundaries of Contra Costa County are established.

February 18, 1850: In accordance with the State Constitution, it was provided that the State be divided into counties. The first State Legislature, which began in December 1849, passed "An Act subdividing the State into counties and establishing seats of justice herein" on February 18, 1850. So begins Contra Costa County, one of California’s original 27 counties. Initially, it covered the entire East Bay and “contra costa” indicated it was the opposite coast from San Francisco. In 1853, Alameda County was carved primarily from Contra Costa and is now that opposite shore.

Early Peoples

People have lived in this area for some 13,000 years. At the time of Spanish contact, they were called Bay Miwok, Ohlone and Northern Valley Yokuts. Sustained by rich natural resources, each tribe knew its territory and had a culture which changed very slowly over time.

The first European expedition to travel through the county was led by Lt. Pedro Fages and recorded by Father Juan Crespi in 1772. Missions were established and western diseases ultimately decimated the native population. Established in 1797, cattle from Mission San Jose grazed in central Contra Costa during drought years.

After the missions were secularized, fifteen Mexican ranches were granted throughout the county. The first was Ignacio Martinez’ Rancho El Pinole in 1829. Other prominent rancheros included Francisco Castro, Juan Bautista Alvarado (the governor of Alta California from 1837 to 1842 who married Marina Castro), Salvio Pacheco and Jose Maria Amador.

American California

Americans John Marsh and Elam and Margaret Brown settled early in Brentwood (1837) and Lafayette (1847). In 1848 after the Mexican-American War ended and gold was discovered, immigrants rushed to California and the cities of Martinez and New York Landing (Pittsburg) became important portals for miners to reach the Sierra. With statehood in 1850, Martinez became the County seat.

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The above is an excerpt from the program written by Beverly Lane, CCCHS Board of Directors, for the April 2013 CCCHS exhibit “Contra Costa County: More Than the Opposite Coast”. For a copy of the full program, including Beverly’s main sources, contact CCCHS at (925) 229-1042 or email info@cocohistory.org.

Copies of The History of Contra Costa County, originally published by Slocum & Co. in 1882, may be purchased at the CCCHS Bookstore, in-person or online.