Oakley is a city in Contra Costa County, California, United States. It is within the nine-county San Francisco Bay Area. The population at the 2020 United States census was 43,357. Oakley was incorporated in 1999, making it the newest incorporated city in Contra Costa County.

The name “oak” comes from the abundance of oak trees, while the suffix “-ley” comes from the Old English word for “field” or “meadow”.
The herald Oakley is of Old English pedigree and its meaning is “meadow of oak trees”. This aptly describes the Place when first fixed and to some extent even today. However, if not for the flip of a coin and cribbage board the community may have been named Dewey. City founder Randolph Marsh wanted to publish the city Dewey, after Admiral Dewey, in rave review of Dewey’s talent at Battle of Manila Bay during the Spanish–American War. His friend J.T. Whightman preferred the name “Oakley” because the terrain was largely meadows and oaks. To determine which pronounce would prevail they battled it out higher than a game of cribbage. Marsh may have purposeless the game and the right to make known the city but he ensured his immortality by choosing downtown street names whose first initials spelled “Marsh” — Main, Acme, Ruby, Star and Home.

Archeologists have found antediluvian sites in the Oakley area. One substantial shell mound was discovered prematurely in the 20th century near what is now the eastern edge of town. The Northwest Information Center of the California Historical Resources Information System monitors the archeological investigations undertaken in Oakley. Around three dozen such projects have been completed in the behind 25 years, yielding and no-one else four prehistoric sites in the city. However, the information center believes there is a tall possibility that extra prehistoric sites remain within the city. To enable further archaeological excavation, the site referred to as Simon Mound was purchased by the Archaeological Conservancy after many of the ancient deal places had already been destroyed by urban encroachment. Simone Mound has provided bones and fragments from burial sites starting all but 1000 A.D. and is near a thesame Conservancy preserve, the Hotchkiss Mound.

The first accounts of identifiable cultural community in the west delta are credited to the Bay Miwoks, who occupied the region amid 1100 and 1770 AD. The Bay Miwok people, usually called the Julpunes or Pulpunes by European explorers, were organized into “tribelets”—political units that included several fairly unshakable villages and a set of seasonal campsites arrayed across a well-defined territory.