Miwok Indians inhabited this valley at the base of Mt. Diablo when Spanish explorers came in the 1770's. Scouts, trappers, prospectors and settlers followed.
In 1857 Clayton was founded by Joel Clayton, a miner, farmer, and wagonmaster from England. Coal, copper and quicksilver mines developed nearby, creating a bustling downtown with stage service and a post office established in 1861. When mining declined, farming and ranching prospered, with orchards, vineyards, horses and cattle.
Eventually residential development blended with this historical setting. To preserve its unique identity and rural charm, Clayton incorporated in 1964.