These groups established various villages and settlements throughout the region that were interconnected by a series of extensive trails.

[10][11][12] Wa'aachnga was a major Tongva village site, also occupied by the Serrano and Cahuilla, located near what is now the city of San Bernardino.

[10] By the late 1700s, villages in the area were being increasingly encroached upon by Spanish soldiers and missionaries, who were coming into the region from Mission San Gabriel.

[10][11] Spanish Missionaries from Mission San Gabriel Arcángel established a church at the village of Wa'aachnga, which would be renamed Politania in 1810.

[14] In 1819, they established the San Bernardino de Sena Estancia, a mission farm in what is now Redlands.

Agua Mansa was the first town in what became San Bernardino County, settled by immigrants from New Mexico on land donated from the Rancho Jurupa in 1841.

About 390,000 residents live just north of the San Bernardino Mountains, in and around the roughly 280 square-mile area that includes the Victor Valley.

Further south, a portion of Joshua Tree National Park overlaps the county near the High Desert area, in the vicinity of Twentynine Palms.

The mountains are home to the San Bernardino National Forest, and include the communities of Crestline, Lake Arrowhead, Running Springs, Big Bear City, Forest Falls, and Big Bear Lake.

The San Bernardino Valley includes the cities of Ontario, Chino, Chino Hills, Upland, Fontana, Rialto, Colton, Grand Terrace, Montclair, Rancho Cucamonga, San Bernardino, Loma Linda, Highland, Redlands, and Yucaipa.

Republican Donald Trump carried the county in 2024, flipping it for the first time in a presidential race since 2004.

In past presidential elections, Democrat Joe Biden carried the county by a majority and by double digits as well as Hillary Clinton in 2016.

The heavily Latino cities of Ontario and San Bernardino went for John Kerry in 2004 but with a relatively low voter turnout.

[49] On November 4, 2008, San Bernardino County voted 67% for Proposition 8, which amended the California Constitution to ban same-sex marriages.

Supervisor Bill Postmus pleaded guilty to 10 felonies in regard to his previous post as county assessor.

2022, the county's insurance company, Ironside, balked at paying the settlement, claiming that the county willfully "retaliate[d] against the Colonies II Plaintiffs as part of a decades-long dispute over land and water rights in Upland, California, culminating in a malicious prosecution of Burum.

[64][65][66][67][68] A referendum in 2022 requesting the county board seek a "fair share" of government funding, by means including secession, narrowly passed.

[73] According to the California Secretary of State, as of February 2020, there were 1,016,190 registered voters in San Bernardino County.

[86] As of April 2019 the City of Victorville declined to renew their contract with The San Bernardino County Fire Department.

[87] The current district attorney is Jason Anderson, who was elected in March 2018 and took office on January 1, 2019.

On December 2, 2015, in the city of San Bernardino, terrorists attacked a staff meeting being held in the Inland Regional Center, murdering 14 people and wounding 22.

Its exhibits and collections draw from the cultural and natural history of San Bernardino County.

The Center for Biological Diversity, the Sierra Club and the Audubon Society also sued in a separate case.

According to Brendan Cummings, a senior attorney for the plaintiffs: "San Bernardino has never seen a project it didn't like.

The plaintiffs want the county to rewrite its growth plan's environmental impact statement to include methods to measure greenhouse gases and take steps to reduce them.

However, the county says it will make sure employment centers and housing are near transportation corridors to reduce traffic and do more to promote compact development and mass transit.

According to the LA Times in 2015, San Bernardino County had the highest levels of ozone in the United States, averaging 102 parts per billion.