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Encyclopedia > Contra Costa County
Image:California map showing Contra Costa County.png

Contra Costa County is a suburban county in California's San Francisco Bay Area. As of the 2000 census it had a population of 948,816. The county seat is Martinez.




In prehistoric times, particularly the Miocene epoch, portions of the landforms now in the area (then marshy and grassy savanna) were populated a wide range of now extinct mammals, known in modern times by the fossil remains excavated in the southern part of the county. These included pigs the size of modern rhinoceros and rhinoceri the size of modern pigs. In the northern part of the county significant coal deposits were formed in even earlier geologic eras. Other areas of the county have ridges exposing ancient but intact (not fossilized) seashells, imbedded in sandstone layers alternating with limestone. Layers of volcanic ash ejected from geologically recent but now extinct volcanos, compacted and now tilted by compressive forces may be seen at the side of some road excavations. This county is an agglomeration of several distinct geologic terrains, as is most of the greater San Francisco Bay Area, which one of the most geologically complex regions in the world. The great local mountain Mount Diablo has been formed and continues to be elevated by compressive forces resulting from the forces of plate tectonics and at its upper reaches exposes ancient seabed shale rock scraped from their distant sedimentation location and elevated by these great forces.

Native American period

There is an extensive but little recorded human pre-columbian history in this area, with the present county containing portions of regions populated by a number of native American tribes. Although the earliest occupation by modern man (homo sapiens) appears to be about six to ten thousand years before the present period, these numbers are not definitive and may possibly extend to far earlier times, at least as far as non–settling populations are concerned. The known settled populations were were hunter-gatherer societies that had no knowlege of metals and that produced utilitarian crafts for everyday use (especially woven reed baskets) of the highest quality and with graphic embellishments of great ęsthetic appeal. Extensive trading from tribe to tribe transferred exotic materials such as obsidian (useful for the making of arrowheads) throughout the region from far distant Californian tribes. Unlike the nomadic native American of the Great Plains it appears that these tribes did not incorporate warfare into their culture but were instead generally cooperative. Within these cultures the concept of individual or collective land ownership was nonexistent. As the culture and its values was not respected by either the first Spanish colonizers (who considered the natives both heathans to be converted to Christianity and easily enslavable labor) nor the second U.S.A occupiers (who did their best to exterminate them), little of their history, lore or culture was recorded at the time. Most of what is known culturally comes from preserved contemporaneous and excavated artifacts and from inter-generational knowledge passed down through northerly outlying tribes of the larger region.

Spanish colonial

Early interaction of these native Americans with Europeans came with the Spanish colonization via the establishment of missions in this area, with the missions in San Jose, Sonoma, and San Francisco and particularly the establishment of the Presidio of San Francisco (a military establishment) in 1776. Although there were no missions established within this county, Spanish influence here was direct and extensive, through the establishment of land grants from the King of Spain to favored settlers. These rancheros were not small farms, but extremely large — a modern county would accommodate only a few of them. With the land came the right to rule over its inhabitants, both native and immigrant laboring individuals and families.

Mexican provincial

With the signing of the treaty of Guadilupe Heldago in 1821 Mexico gained independence from Spain. Insofar as ranchero life was concerned in the remote provence centered upon San Francisco, little was changed.

Bear Flag Republic and the Statehood of California

This was to change rapidly in 1848 with California's gold rush, and the Bear Flag Revolt, where a few settlers from the United States declared a short-lived republic, immediately petitioning for statehood. The land titles in Contra Costa County may be traced to multiple subdivisions of a few original Spanish land grants from the King of Spain. Reminders of these grants may be seen the grantee's family names in a few city and town names such as Martinez, Pacheco and Moraga, with their subsequent divisions into large farms and orchards remembered in the names of streets, residential subdivisions, and business parks. A few mansions from the more prosperous farms have been preserved as museums and cultural centers and one has been preserved as a working demonstration ranch.

Contra Costa's creation and division

Contra Costa County was one of the original counties of California, created in 1850 at the time of statehood. The county was originally to be called Mt. Diablo County, but the name was changed prior to incorporation as a county. The county's Spanish language name means opposite coast, because of its location opposite San Francisco, in an easterly direction, on San Francisco Bay. Southern portions of the county's territory, including the all of the bayside portions opposite San Francisco, and Northern portions of Santa Clara County were given up to form Alameda County in 1853.

Orchards, farms, and ranches

The great rancheros of the Spanish period were divided and sold for agricultural uses, with intensively irrigated farming made possible in some areas by the development of canals that brought water from the eastern riverside portions of the county to the central portion. Other areas could used the more limited water available from local creeks and from wells. Orchards dominated where such water was available, while other, seasonally dry areas were used for cattle ranching. In central county Walnuts were an especially attractive orchard crop, using the thin shelled English Walnut branches grafted to the hardy and disease resistant American Walnut root stock. In the Moraga region, pears dominated, and many old (but untended) roadside trees are still picked seasonally by passers by. In eastern county, stone fruit, especially cherries, is still grown commercially, with many seasonal opportunities offered for people to pick their own fruit for a modest fee.


The western terminus of the transcontinental railroad route is in Oakland, California, located in Alameda County. From Oakland, there are two primary routes east:

  • To the south of Oakland, then east through Niles Canyon, across the Livermore valley, and through Altamont Pass to the great Central Valley, ulitimately crossing the Sierra Nevada Mountains through Donner Pass.
  • To the north of Oakland, through Richmond and along the north coast of Contra Costa County. A great railroad bridge crosses parallel to Interstate Highway 680. Originally part of the Feather River Route that particular crossing of the Sierra Nevada is no longer used for passenger traffic. Rail traffic also proceeds north through Portland, Oregon to Seattle, Washington, with the Amtrac Coast Startlight completing service through Oakland from Los Angeles.

There were a large number of short lines in the county between the late 19th century and the early 20th century. The rights of way of a number of these railroads also served as utility rights of way, particularly for water service, and so were preserved, and in the late 20th century enhanced as walking, jogging, and bicycle riding trails in the central portion of the county.

Much of the western area of the county was well served by the trans-bay electrified commuter rail lines of the Key System, until its ultimate decline in the late 1940's.


A concrete-lined and fenced irrigation canal still makes a loop through central county and provided industrial and agricultural grade water to farms. While no longer used for extensive irrigation, it is still possible for adjoining landowners (now large suburban lot owners) to obtain pumping permits. Most of this water is destined for the heavy industry near Martinez. As with the railroad rights of way there is now an extensive public trail system along these canals.

Heavy industry

View of the Shell/Valero Martinez oil refinery

Owing to its extensive waterfront on San Francisco, San Pablo, and Suisun bays the northwestern and northern segments have long been sites for heavy industry, including the a number of still active oil refineries (particularly Standard Oil in Richmond and Shell/Valero in Martinez) chemical plants and once substantial integrated steel plant that are now reduced to secondary production of strip sheet and wire. The San Joaquin River forms a continuation of the northern boundary turns southward to form the eastern boundary of the county. Some substantial Sacramento Delta "islands" (actually leveed former marshes) are included in this corner of the county.


During World War II, Richmond hosted one of the two Bay Area sites of Kaiser Shipyards and wartime pilots were trained at what is now a civil airfield in Concord. Additionally, a large Naval Weapons Depot and munitions ship loading facilities at Port Chicago remain active to this day. The loading docks were the site of a devastating explosion. Port Chicago was bought out and demolished by the Federal Government to form a safety zone near the Naval Weapons Station loading docks. At one time there was a dynamite factory (subsequently closed) at the town of Hercules.

Early postwar period

With the postwar baby boom and the desire for suburban living, large tract housing developers would purchase large central county farmsteads and develop them with roads, utilities and housing. Once rural walnut orchards, the area was first developed as low cost, large lot suburbs, with a typical low cost home being placed on a "quarter acre" lot — actually a little less at 10,000 square feet (930 m²). Much of the expansion of these suburban areas was attributable to "white flight", although in this region (known famously for its liberal political bias) more due to economics, a desire for a more rural environment, and a higher school quality than race.

Technical innovators

In the 1970's and 80's many small and innovative technical firms were started in this county, most of which are no longer present, having either failed, been absorbed into larger corporations, or having outgrown their original location are now elsewhere in the bay area.

Corporate headquarters

During the 1980's and early 1990's, many corporations that were formerly housed in the more central metropolitan area followed their employees by moving to large suburban and edge city office areas and office parks.

A number of large corporations now have headquarters in large developments along what is called the 680 corridor, that segment of Interstate Highway 680 that extends from Concord in the north to San Ramon in the south, continuing into inland Alameda County from Dublin to Pleasanton.

West County

The housing stock in the region was extensively developed after the great San Francisco Earthquake of 1906. Much of the housing stock in these areas is becoming quite expensive. As an alternative to moving to either the very expensive central county, or the too-distant East County, this area is becoming gentrified, with a mix of races and income levels — a character actively sought by some housing purchasers. The downside of this is a corresponding lack of affordable housing for those in lower paying service jobs — a problem endemic throughout the region. As the public schools are not of the quality seen in the central county, many of the middle class residents of the area send their children to expensive private schools, further limiting the availability of resources to the public schools.

Central County

The valley traversed by Interstate 680, by State Highway 24, and by portions of Interstate highway 580 (the Livermore Valley) are collectively called the Tri-Valley Area. West of this area are the cities near or on San Francisco and San Pablo bays, while east of this area is the Sacramento-San Juaquin river delta and California's Great Central Valley. The three major (and prosperous) towns east of the hills on or near Highway 24 and their surrounding areas (Lafayette, Moraga and Orinda) are collectively known as Lamorinda. Owing to the high quality of its public schools (due largely to both demographics and added support from prosperous parents), this area has become a magnet for well off families with children. This has driven (through normal supply-demand economics) the price of housing to astounding levels. An original, unmodified one bath, three bedroom large-lot house built in the late 1940s is now priced out of the range of those with the typical median income for the region. As the taxes on long occupied houses are quite low, owing to the tax-limiting Proposition 13, there is little incentive for "empty nesters" to move away, further limiting the supply for new entrants to the market. Proposition 13 has also discouraged the "upgrade move", instead encouraging extensive remodeling of existing owner–occupied buildings. This has lead to beneficial stability in some neighborhoods, further increasing the desirability of many locations. While there are small patches where houses are completely torn down and replaced with larger, more modern houses, this is less economically attractive (owing to the high cost of purchase) than is the practice of extensive remodeling, refurbishment, and expansion via the addition of a large master suite and removal of interior partitions to create larger rooms. There are a number of speculative remodelers who will refurbish an unoccupied structure over a period of a year, using high quality materials and finishes, yet making enough profit to provide a comfortable living. Although the pace housing sales has slowed recently (2004), prices continue to increase and the market remains attractive to the remodeling industry.

In this way the central county region has become a mix of older suburbs, newer developments, small lot "infill" developments, and extensive shopping areas.

East County

Lower cost modern tract developments continue along Suisun Bay and into rural "East County" - new "bedroom" communities" to serve the now "edge cities". This results in some incredibly long and slow commutes for some county residents, as roadbuilding is (as usual) unable to keep pace with the development patterns. Some political control has been established to restrict the development somewhat, with "urban limit lines" now established, but yet to prove their long term effectiveness.

Urban decay at the fringes

Other cities in the once heavily industrialized northwestern and western waterfront areas such as Richmond and Bay Point (formerly West Pittsburg) have fallen on harder times, with Richmond having difficulty balancing its school budget. This may be arguably attributed to a side effect of proposition 13: it applies also to large industrial and merchandising companies, which have seen their share of property taxes (the bulk of which is used to support local schools) decline severely. As housing prices have not kept pace with the more central and outlying regions, the school districts are having difficulty obtaining proper funding. A lack of the availability of the kind of community support available in the more prosperous regions also contributes to the problem, with higher income residents of some of these declining areas sending their children to private schooling, creating a self reenforcing decline in the public schools.


There are currently political fights over the potential redevelopment of the county seat (Martinez), with long term residents and many elsewhere in the county concerned that it will loose its remaining small-town charm and utility in an effort to become more like the county's major recreational shopping center of Walnut Creek.


According to the U.S. Census Bureau, the county has a total area of 2,078 km² (802 mi²). 1,865 km² (720 mi²) of it is land and 213 km² (82 mi²) of it is water. The total area is 10.25% water.

It is bounded on the south and west by Alameda County, on the northwest San Francisco Bay, on the North by San Pablo Bay and Suisun Bays, and on the east by the San_Joaquin_River.


The most notable natural landmark in the county is Mount Diablo, at the northerly end of the Diablo Range.


As of the census2 of 2000, there are 948,816 people, 344,129 households, and 242,266 families residing in the county. The population density is 509/km² (1,318/mi²). There are 354,577 housing units at an average density of 190/km² (492/mi²). The racial makeup of the county is 65.50% White, 9.36% Black or African American, 0.61% Native American, 10.96% Asian, 0.37% Pacific Islander, 8.06% from other races, and 5.13% from two or more races. 17.68% of the population are Hispanic or Latino of any race.

There are 344,129 households out of which 35.40% have children under the age of 18 living with them, 54.50% are married couples living together, 11.50% have a female householder with no husband present, and 29.60% are non-families. 22.90% of all households are made up of individuals and 8.00% have someone living alone who is 65 years of age or older. The average household size is 2.72 and the average family size is 3.23.

In the county the population is spread out with 26.50% under the age of 18, 7.70% from 18 to 24, 30.60% from 25 to 44, 23.90% from 45 to 64, and 11.30% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 95.40 males. For every 100 females age 18 and over, there are 92.20 males.

The median income for a household in the county is $63,675, and the median income for a family is $73,039. Males have a median income of $52,670 versus $38,630 for females. The per capita income for the county is $30,615. 7.60% of the population and 5.40% of families are below the poverty line. Out of the total population, 9.80% of those under the age of 18 and 6.00% of those 65 and older are living below the poverty line.

Cities and towns

Other named regions and developments

  • Saranap
  • Rossmoor (A senior development incorporated into Walnut Creek, not the Southern California Rossmoor)

Museums and Historic sites

Parks and related places

  • Briones Regional Park (http://www.ebparks.org/parks/briones.htm)*
  • Diablo Foothills (http://www.ebparks.org/parks/diablo.htm)
  • Howe Homstead Park (http://www.ci.walnut-creek.ca.us/openspace/oshowe_homestead.htm)
  • Mount Diablo State Park
  • Las Trampas Regional Wilderness (http://www.ebparks.org/parks/lastram.htm)*
  • Shell Ridge Open Space (http://www.ci.walnut-creek.ca.us/openspace/shell_ridge.htm)
  • Lime Ridge Open Space (http://www.ci.walnut-creek.ca.us/openspace/oslime_ridge.htm)
  • San Pablo Recreation Area (http://www.ebmud.com/services/recreation/east_bay/san_pablo/default.htm) (San Pablo Dam Reservoir) - Read caution if eating fish caught here.
  • Sugarloaf Open Space (http://www.ci.walnut-creek.ca.us/openspace/sugarloafpage.htm)
  • Acalanes Open Space (http://www.ci.walnut-creek.ca.us/openspace/osacalanes.htm)
  • *Adjoining or nearby these parks are lands of the East Bay Municipal Utility District. These require special annual permits for hiking, bicycle riding and horse riding, available for a small fee. At least one member of a party traversing these areas must have such a permit.


  • Iron Horse Regional Trail
  • State Riding and Hiking Trail (http://www.ebparks.org/parks/calrhktr.htmCalifornia)
  • Contra Costa Canal Regional Trail (http://www.ebparks.org/parks/canaltr.htm)
  • Delta de Anza Regional Trail (http://www.ebparks.org/parks/deanza.htm)
  • Briones-Mount Diablo Regional Trail (http://www.ebparks.org/parks/brdiotr.htm)
  • Lafayette-Moraga Regional Trail (http://www.ebparks.org/parks/canaltr.htm)
  • Marsh Creek Trail (http://www.ebparks.org/parks/marshtr.htm)

External links

  • Contra Costa County government information (http://www.co.contra-costa.ca.us/)
Counties and Largest Cities in California
Cities: Anaheim | Bakersfield | Fremont | Fresno | Glendale | Huntington Beach | Long Beach | Los Angeles | Modesto | Oakland | Oxnard | Riverside | Sacramento | San Bernardino | San Diego | San Francisco | San Jose | Santa Ana | Stockton
Counties: Alameda | Alpine | Amador | Butte | Calaveras | Colusa | Contra Costa | Del Norte | El Dorado | Fresno | Glenn | Humboldt | Imperial | Inyo | Kern | Kings | Lake | Lassen | Los Angeles | Madera | Marin | Mariposa | Mendocino | Merced | Modoc | Mono | Monterey | Napa | Nevada | Orange | Placer | Plumas | Riverside | Sacramento | San Benito | San Bernardino | San Diego | San Francisco | San Joaquin | San Luis Obispo | San Mateo | Santa Barbara | Santa Clara | Santa Cruz | Shasta | Sierra | Siskiyou | Solano | Sonoma | Stanislaus | Sutter | Tehama | Trinity | Tulare | Tuolumne | Ventura | Yolo | Yuba |

  Results from FactBites:
Contra Costa County, California - Wikipedia, the free encyclopedia (3208 words)
Contra Costa County was one of the original counties of California, created in 1850 at the time of statehood.
It is bounded on the south and west by Alameda County, on the northwest San Francisco Bay, on the North by San Pablo Bay and Suisun Bays, and on the east by the San_Joaquin_River.
In the county the population is spread out with 26.50% under the age of 18, 7.70% from 18 to 24, 30.60% from 25 to 44, 23.90% from 45 to 64, and 11.30% who are 65 years of age or older.
  More results at FactBites »



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