Los Alamitos is a city in Orange County, California. The city was incorporated in March 1960. The population was 11,780 at the 2020 census, up from 11,449 at the 2010 census. The adjacent unincorporated community of Rossmoor uses the same 90720 ZIP code in its mailing address, but is not part of the city. The Los Alamitos Race Course is named for the city, but lies in the neighboring city of Cypress.

Rossmoor is a planned census-designated place located in Orange County, California. As of the 2020 census, the CDP had a total population of 10,625 up from the 2010 census population of 10,244. The gated Leisure World retirement community in the city of Seal Beach is to the south of Rossmoor, Los Alamitos is to the east and north, and Long Beach is to the west. The community of Rossmoor has two shopping centers within its boundaries, but only one—the Rossmoor Village Square, is now within the political boundaries of Rossmoor. A larger shopping center, the Rossmoor Business Center, was annexed, despite many protests, by the City of Seal Beach in 1967. The Center has been remodeled several times and was renamed the Shops at Rossmoor in the early 2000s.