[8] The Mare Island Naval Shipyard was founded in 1854, and defined Vallejo's economy until the turn of the 21st century.

Vallejo was once home of the Coast Miwok as well as Suisunes and other Patwin Native American tribes.

The California Archaeological Inventory has indicated that the three Indian sites are located on Sulphur Springs Mountain.

The city was named after this Mexican military officer and title holder who was appointed in settling and overseeing the North Bay region.

In 1846, independence-minded Anglo immigrants rose up against the Mexican government of California in what would be known as the Bear Flag Revolt which resulted in Gen. Vallejo's imprisonment in Sutter's Fort.

In 1851, Vallejo was declared to become the official California State Capitol, with the new government prepared to meet for the first time the following year.

In 1853, it was again the meeting place for the legislature, solely for the purpose of moving the capitol officially to Benicia, which occurred on February 4, 1853, after only a month.

After the legislature left, the government established a naval shipyard on Mare Island, which helped the city overcome the loss.

Due to the presence of the shipyard, Filipinos began to immigrate to Vallejo beginning in the first decades of the 20th century.

Afterward, Vallejo remained active in state politics, but challenges to his land titles around Sonoma eventually left him impoverished and reduced his ranch from 250,000 acres to a mere 300.

He eventually retired from public life, questioning the wisdom of his having welcomed the American acquisition of California in the first place.

[13] Mare Island Naval Shipyard was a critical submarine facility during WW II, both for constructing and overhauling vessels.

Reportedly, salaries and benefits for public safety workers accounted for at least 80 percent of Vallejo's general-fund budget.

[16] According to United States Census Bureau, the city has a total area of 49.5 square miles (128 km2).

Vallejo borders the city of Benicia to the east, American Canyon and the Napa county line to the north, the Carquinez Strait to the south and the San Pablo Bay to the west.

No quaternary seismic activity along these minor faults has been observed with the possible exception of a slight offset revealed by trenching.

Vallejo has a mild, coastal Mediterranean climate and can be an average of 10 °F (−12 °C) cooler than nearby inland cities.

This seasonal lag sees October averages being higher than in May[18] in spite of it being after the Equinox (meaning less daylight than darkness).

Vallejo was named the most diverse city in the United States in a 2012 study by Brown University based on 2010 census data,[22][23] and the most diverse city in California by a Niche study based on 2017 American Community Survey data.

[24] In 2022, Vallejo was again named the most diverse small town in America, with a 77% chance any two residents would be of a different census racial category.

[30] As of 2009, Vallejo is the 9th largest city in the San Francisco Bay Area, 50th in the state of California, and 215th in the U.S. by population.

[35] As early as the 1940s and before, Vallejo is known to have had a well-formed gay community, which was a short drive or boat ride away from San Francisco.

The school agreed to pay her $25,000, adopt a more stringent non-discrimination policy, and include a curriculum that positively portrayed gay and lesbian people.

Residents of Vallejo participate in elections for Solano County Board of Supervisors Districts 1 and 2.

[43][44] As of September 2022, there were 69,546 registered voters in Vallejo; of these, 40,818 (58.7%) are Democrats, 8,751 (12.6%) are Republicans, and 15,612 (22.4%) stated no party preference.

On April 17, 2012, the City Council approved the first citywide participatory budgeting (PB) process in the United States.

[47] Vallejo has seen a rate of killings by police officers that is significantly higher than the national average and other Bay Area cities.

[56] Vallejo is accessible by Interstate 80 between San Francisco and Sacramento, and is the location for the northern half of the Carquinez Bridge.

It is also accessible by Interstate 780 from neighboring Benicia to the east, and by Route 37 from Marin County to the west.

[57][58][59][60] Open Vallejo is an independent, nonprofit public interest newsroom primarily focused on investigative and explanatory reporting.