Formerly an independent town, it has been a neighborhood of San Jose since the 1950s,[3] though some portions are still unincorporated as a census-designated place.

[4] Alum Rock is one of San Jose's most notable and historic Chicano/Mexican-American districts.

During the 1940s and 1950s, developers began building housing and formed the community of Alum Rock.

In the 1980s and 1990s, the neighborhood became older and increasingly populated with Latino immigrants as "white flight" affected the area of East San Jose.

Today, Alum Rock remains a distinct community separated from the rest of San Jose.

Alum Rock is a vast district of East San Jose, made up of numerous smaller neighborhoods.

[8] Neighborhoods include Little Portugal, Little Saigon, Mayfair, King & Story, East Foothills, Alum Rock Village, Mount Pleasant, among others.

Alum Rock is bound by the Diablo Range to the east, Coyote Creek to the west, Mabury Road to the north and Ocala Avenue to the south.

The 2010 United States Census[25] reported that Alum Rock had a population of 15,536.

There were 3,863 housing units at an average density of 3,207.3 per square mile (1,238.3/km2), of which 2,393 (64.9%) were owner-occupied, and 1,293 (35.1%) were occupied by renters.

In the California State Legislature, Alum Rock is in the 15th Senate District, represented by Democrat Dave Cortese, and in the 27th Assembly District, represented by Democrat Esmeralda Soria.