The San Gabriel Valley, often referred to by its initials as SGV, is one of the principal valleys of Southern California, with the city of Los Angeles directly bordering it to the west, and occupying the vast majority of the southeastern part of Los Angeles County. Surrounding landforms and other features include the following:the San Gabriel Mountains to the north; the San Rafael Hills to the west, with the Los Angeles Basin beyond; the Crescenta Valley to the northwest; the Puente Hills to the south, with the coastal plain of Orange County beyond; the Chino Hills and San Jose Hills to the east, with the Pomona Valley and Inland Empire beyond; and the city limits of Los Angeles, bordering its western edge.

Whittier is a city in Southern California in Los Angeles County, part of the Gateway Cities. The 14.7-square-mile (38.0 km2) city had 87,306 residents as of the 2020 United States census, an increase of 1,975 from the 2010 census figure. Whittier was incorporated in February 1898 and became a charter city in 1955. The city is named for the Quaker poet John Greenleaf Whittier and is home to Whittier College. The city is surrounded by three unincorporated areas sharing the Whittier name, West Whittier-Los Nietos, South Whittier, and East Whittier, which combined are home to a larger population than Whittier proper.