The Historical Society of Long Beach (HSLB) was formed in 1962 with the mission to collect, preserve, and present the city’s history. Throughout the years the HSLB has occupied many locations around the city, settling at its current location in Bixby Knolls in 2007. Operations are sustained at the HSLB by grant funding, membership dues, and community fundraising through programs and events.

Documents and photos relating to the history of the Crescenta Valley. The La Crescenta Valley Historical Society has a lot of materials on the New Years Flood of 1934, and the town of Montrose, plus some materials on the American portrait artist S. Seymour Thomas.

The Mojave Desert Archives preserves the history of transcontinental travel to the Los Angeles region through the Mojave Desert of eastern California. Route 66, National Old Trails Road, the Mojave Wagon Road, the Santa Fe Railway (now BNSF), Union Pacific Railroad, and Interstate highways were and are major transit routes through the desert terminating in the Los Angeles basin.

Mount Saint Mary's University was founded by the Sisters of St. Joseph of Carondelet in 1925 as the first Catholic women's college west of the Mississippi. It comprises two historic sites, the Chalon Campus high above Brentwood (1930), and the Doheny Campus, which occupies the former estate of Edward and Estelle Doheny, including the Doheny Mansion at 8 Chester Place (1899).