Martinez  is a city and the county seat of Contra Costa County, California, United States, in the East Bay region of the San Francisco Bay Area. Located on the southern shore of the Carquinez Strait, the city’s population was 38,290 at the 2020 census. The city is named after Californio ranchero Ygnacio Martínez, having been founded on his Rancho El Pinole. Martinez is known for its historic center and its waterfront.

Martinez was the home of naturalist John Muir from 1880 until his death in 1914. He was buried about a mile south of the building that is now the John Muir National Historic Site. Also nearby is the Vicente Martinez Adobe, built in 1849 by the son of Ygnacio Martinez.

The first post office opened in 1851.

In 1860, Martinez played a role in the Pony Express, where riders would take the ferry from Benicia (particularly if they missed the steamer in Sacramento).

The first oil refinery in the Martinez area was built in 1904 at Bull’s Head Point, a then-unincorporated waterfront area two miles east of the downtown district. That area soon became known as Mococo, following the 1905 arrival of a smelting works, operated by the Mountain Copper Company (Mo Co Co).

Geography

According to the United States Census Bureau, the city has a total area of 13.1 square miles, of which 1.0 square mile (7.64%) is covered by water.

The city is largely surrounded by water and regional open-space preserves. The Martinez–Benicia Bridge carries Highway 680 across the eastern end of the Carquinez Strait to Solano County. The city is a densely built downtown valley threaded by Alhambra Creek and north of Highway 4. Suburban areas stretch south of Highway 4 to join the neighboring city of Pleasant Hill. Unincorporated areas include the rural Alhambra Valley and the Franklin Canyon area.

Martinez is one of the only two places in the Bay Area, the other being Golden Gate Bridge, where the Bay Area Ridge Trail and the San Francisco Bay Trail converge. The Bay Trail is a planned recreational corridor that, when complete, will encircle San Francisco and San Pablo bays with a continuous 400-mile network of bicycling and hiking trails. It will connect the shoreline of all nine Bay Area counties, link 47 cities, and cross the major toll bridges in the region, including the Benicia–Martinez Bridge. To date, approximately 240 miles of the alignment—over half the Bay Trail’s ultimate length—have been completed. The Bay Area Ridge Trail ultimately will be a 500+ mile trail encircling the San Francisco Bay along the ridge tops, open to hikers, equestrians, mountain bicyclists, and outdoor enthusiasts of all types. So far, over 300 miles of trail have been dedicated for use. East Bay Regional Park District’s Iron Horse Regional Trail will join the Bay Trail along the waterfront, and the Contra Costa Canal Trail threads through the city from Pleasant Hill to the south.

Census

The 2020 United States Census reported that Martinez had a population of 38,290. The population density was 2,727.4 inhabitants per square mile. The racial makeup of Martinez was 27,603 (77.1%) White, 1,303 (3.6%) African American, 255 (0.7%) Native American, 2,876 (8.0%) Asian, 121 (0.3%) Pacific Islander, 1,425 (4.0%) from other races, and 2,241 (6.3%) from two or more races. Hispanic or Latino of any race were 5,258 persons (14.7%).

The Census reported that 34,528 people (96.4%) lived in households, 235 (0.7%) lived in non-institutionalized group quarters, and 1,061 (3.0%) were institutionalized.