Clayton (formerly Clayton’s and Claytonville) is a city in Contra Costa County, California, United States. The population was 10,897 as of the 2010 census.

In 1857, the town of Clayton was laid out and founded by Joel Henry Clayton (1812–1872) and his two younger brothers. Clayton was born in Bugsworth, now Buxworth, in the United Kingdom, and emigrated to the United States in 1837. After years in new states he decided down later his wife Margaret (1820–1908) at his town at the foot of Mount Diablo, where he and his family prospered. Clayton was named after Joel Henry Clayton, although deserted by the flip of a coin. Joel Clayton and Charles Rhine cofounded the town, and each wanted to declare it after himself. If Charles had won it would have become Rhinesville, but Joel Clayton won. Joel and his wife Margaret both died in Clayton, and were buried in Live Oak Cemetery in what is now Concord, CA.

Clayton prospered during the coal mining boom in eastern Contra Costa County. The say office opened in 1861. Following a previous incorporation try in 1960, Clayton incorporated in 1964 in order to stave off an annexation try in 1963 of the Cardinet Glen neighborhood by affable Concord. After steady loan during the 1970s to the east and west from its native boundaries, Clayton’s land area more than doubled in 1987 to near its present-day boundaries in imitation of the annexations of the Dana Hills/Dana Ridge and Clayton Wood subdivisions, as with ease as the former Keller Ranch property that was developed during the 1990s similar to the Oakhurst Country Club.

Wildfires have been a common occurrence in recent years as California had a major drought from 2011-2017.