Audio Tours of Mount Diablo
Experience an Audio Tour Here
The tours feature lively interviews and music with the rush of wind and the chirps, howls, and growls of wildlife, all downloadable to an audio video media player

Wildflower Identification Guide

calochortus pulchellus logo mjw

Make a Difference and
Donate to MDIA


Donate Through PayPal

Donate Through MDIA's Vehicle Donation Program

Vehicle Donation

These are all great ways for you to support Mount Diablo State Park

Newsletter Sign Up
  1. First Name(*)
    Invalid Input
  2. Last Name(*)
    Invalid Input
  3. Email(*)
    Invalid Input
  4. Are you a real person?
    Invalid Input

View the Sitemap

Visit the Links page


Mount Diablo Cultural History

How Was Contra Costa County Named?

by: Jose Ignacio Rivera

The Portola-Serra Expedition of 1769-1770 was the first real attempt to establish Spanish settlements in Alta California. Baja (Lower) California is the part of the then state that is now in modern-day Mexico and Alta (Upper) California is in the United States. The Portola-Serra Expedition followed the coast northward on foot and horse, while sending another party by ship with supplies. Right about modern-day Pacifica Portola sent a scouting party to the top of the peninsula mountains to hunt for deer meat. A naval officer named Miguel Costanso saw the south bay and reported seeing a large estuary, with a good stand of "madera en la contra costa" (timber on the opposite coast). The expedition was trying to reach Point Reyes, but conditions became too desperate for the Spaniards. Finding the supply ship became the prime goal of the expedition. Later Partola sent Captain Ortega to explore the Contra Costa, to look for a land route to Point Reyes and/or the port containing the supply ship.

By the time of the Fages Expedition in 1772, the use of Contra Costa was a common term for the East Bay. Starting in Monterey the Fages Expedition marched up the coast of the East Bay and were the first Europeans to look through the Golden Gate when they arrived at what is now Berkeley. Fages marched north to the Carquinez Straits, where they met the Karquinez tribe. Near present-day Antioch the explorers turned back. It is here Fages described Mt Diablo, "the slope of the sierra which lies toward Monterey is rather bare of trees but abounds in seeds, and there are many villages near its streams". Fages returned home by way of Kirker Pass, Concord, Walnut Creek and down the San Ramon Valley. When the county was incorporated and the new county fathers were looking for a name, Diablo County headed the list. This recommendation was made in favor of the famous and most prominent natural feature of the county. A core of hard-line religious people blocked the name, so Contra Costa County was chosen as a compromise.

Jose Ignacio Rivera is a State Park Ranger at Mt Diablo State Park and a doctoral candidate in California Ethnohistory, Anthropology Department, UC Berkeley