The county was named after the Estanislao River, which in turn was named in honor of Estanislao, a mission-educated renegade Native American chief who led a band of Native Americans in a series of battles against Mexican troops until finally being defeated by General Mariano Vallejo in 1826.

The county seat was first situated at Adamsville, then moved to Empire in November, La Grange in December, and Knights Ferry in 1862, and was ultimately fixed at the present location in Modesto in 1871.

Because of its proximity to Interstate 5 and the California Aqueduct, some towns within this area, including Patterson and Newman, have experienced tremendous growth and are being transformed into bedroom communities for commuters from the nearby San Francisco Bay Area, while others (including Westley and Crows Landing) have been almost entirely overlooked by development and remain tiny farming communities.

It has only been found in blue oak-gray pine associations in the foothills of the Sierra Nevada, a habitat that occurs at moderately high elevations.

The racial makeup of Stanislaus County was 337,342 (65.6%) White, 14,721 (2.9%) African American, 5,902 (1.1%) Native American, 26,090 (5.1%) Asian (1.5% Indian, 1.1% Filipino, 0.7% Cambodian, 0.5% Chinese, 0.3% Vietnamese, 0.3% Laotian, 0.1% Japanese, 0.1% Korean, 0.1% Cambodian), 3,401 (0.7%) Pacific Islander, 99,210 (19.3%) from other races, and 27,787 (5.4%) from two or more races.

Hispanics or Latinos of any race were 215,658 persons (41.9%); 37.6% of Stanislaus County is Mexican, 0.6% Puerto Rican, 0.5% Salvadoran, 0.2% Nicaraguan, and 0.2% Guatemalan.

[33] (Note - the US Census Bureau says "this system treats race and ethnicity as separate and independent categories.

This means that within the federal system, everyone is classified as both a member of one of the four race groups and also as either Hispanic or non-Hispanic."

About 31.7% of the population were Hispanic or Latino of any race; 8.4% were of German, 6.3% English, 6.0% American, 5.5% Irish, and 5.1% Portuguese ancestry according to Census 2000.

The United States Office of Management and Budget has designated Stanislaus County as the Modesto, CA metropolitan statistical area (MSA).

The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.

The county government is composed of the elected five-member board of supervisors, several other elected offices including the sheriff-coroner, district attorney, tax assessor, auditor-controller, treasurer-tax collector, and clerk-recorder, and numerous county departments and entities under the supervision of the chief executive officer.

The sheriff also provides law-enforcement services by contract to the municipalities of Riverbank, Patterson, Waterford, Salida, and Hughson.

[41] Municipal police departments in the county are: Modesto, population 213,000; Turlock, 73,000; Ceres, 46,000; Oakdale, 23,000; Newman 11,000.

The last Democrat to win a majority in the county was Jimmy Carter in 1976, although Barack Obama won a plurality in 2008 and 2012, as did Bill Clinton in both 1992 and 1996, and as Biden did in 2020.

The Yosemite Community College District covers a 4,500-sq-mi area and serves a population over 550,000, encompassing all of two counties (Stanislaus and Tuolumne) and parts of four others (Calaveras, Merced, San Joaquin, and Santa Clara).