Contra Costa County, California was established on February 18, 1850 and named for its position across the bay from San Francisco! Contra Costa is Spanish for “opposite coast!” Originally, it was going to be named “Mount Diablo County,” but it was widely preferred that they not name the new county after the Devil! Its county seat is Martinez, and its fair is held in Antioch-Pittsburg! You might recognize Mount Diablo, John Muir’s home, the S.S. Red Oak Victory, and the Concord Pavilion, which are located in this county!