Commerce is a city located in southeast Los Angeles County, California, United States. The population was 12,823 at the 2010 census, up from 12,568 at the 2000 census. It is usually referred to as the City of Commerce to distinguish it from the common noun. It is bordered by Vernon on the west, Los Angeles on the northwest, East Los Angeles on the north, Montebello on the east, Downey and Bell Gardens on the south, and Maywood on the southwest. The Los Angeles River forms part of its southwestern boundary, and the Rio Hondo separates it from Downey. Commerce is served by the Long Beach and Santa Ana freeways, as well as the Metrolink commuter rail service at the Commerce station.

Vernon is a city five miles (8.0 km) south of downtown Los Angeles, California, the nearest separate city to downtown Los Angeles. The population was 112 at the 2010 United States Census, the least of any incorporated city in the state. Its population nearly doubled to 222 by the 2020 census, making it the second least populous city in the state after Amador City, whose population grew only slightly—from 185 in the 2010 census, to 200 in the 2020 census.