According to the United States Census Bureau, the CDP has a total area of 2.8 square miles (7 km2), all of it land.

El Sobrante also contains the San Pablo Creek, which runs adjacent to San Pablo Dam road, and adjacent to the El Sobrante - Contra Costa County Library.

[7] After all of the Huichin were removed to Mission San Francisco, they suffered an epidemic of European diseases as well as food shortages, and died in great numbers, resulting in alarming statistics of death and escapes from the missions.

[8] After Mexican independence from Spain in the early 19th century, Spanish colonists were given land grants, one of which was Rancho El Sobrante, deeded to Juan Jose and Víctor Castro in 1841.

The grant's boundaries were unusually complicated, as they were to be determined by the boundaries of the surrounding grants: San Antonio, San Pablo, El Pinole, Boca de la Cañada del Pinole, Acalanes, and La Laguna de los Palos Colorados.

Legal disputes concerning the borders and the claims of squatters continued for four decades, with much of the land sold to pay court and attorney costs.

He built an adobe dwelling in what is now El Cerrito, and became one of the first members of the Board of Supervisors of Contra Costa County.

[10] El Sobrante was called "Oak Grove" by industrial concerns in 1887 when the California and Nevada Railroad put a spur into the area for the purpose of carrying lumber cut from the hills.

[11] Then the name Sobrante was applied, with the addition of the Spanish definite article "El" coinciding with the opening of the first post office in 1941.

[12] By the early 20th century, Rancho El Sobrante had been reduced to a number of smaller ranches, generally following a dirt road along San Pablo Creek.

As roads were paved and homes were constructed, El Sobrante changed from a rural to a semi-rural community.

There were 4,646 residents of Hispanic or Latino ancestry.The 2010 United States Census[15] reported that El Sobrante had a population of 12,669.

The center of the Sikh community is the Gurdwara Sahib of El Sobrante (known for its large golden dome), which sits high in the hills above San Pablo Dam Road.

[20] Former Green Day drummer John Kiffmeyer took his stage name, "Al Sobrante", from the town.