In prehistoric times the valley was inhabited by the Patwin Native Americans, with possible habitation by Wappo tribes in the northwestern foothills. Most villages are thought to have been constructed near the floodplains of watercourses that drain the valley. The maximum prehistoric population is not thought to have exceeded 5000 persons.[1]

Napa County was one of the original counties of California, created in 1850 at the time of statehood. Parts of the county's territory were given to Lake County in 1861. The word napa is of Native American derivation and has been variously translated as "grizzly bear," "house," "motherland" or "fish." Of the many explanations of the name's origin, the most plausible seems to be that it is derived from the Patwin word napo meaning house.

A joke among local youth is that the word means "you will return," referring to the insular nature of the town, and the fact that many of them who try to "escape" to college and elsewhere often end up either coming back or never managing to truly leave at all.