| City/Town/etc. | Population 2020 |
| Los Angeles | 3,898,747 |
| Long Beach | 466,742 |
| Santa Clarita | 228,673 |
| Glendale | 196,543 |
| Lancaster | 173,516 |
| Palmdale | 169,450 |
| Pomona | 151,713 |
| Torrance | 147,067 |
| Pasadena | 138,699 |
| East Los Angeles | 118,786 |
| Downey | 114,355 |
| West Covina | 109,501 |
| El Monte | 109,450 |
| Inglewood | 107,762 |
| Burbank | 107,337 |
| Norwalk | 102,773 |
| Compton | 95,740 |
| Carson | 95,558 |
| Santa Monica | 93,076 |
| South Gate | 92,726 |
| Hawthorne | 88,083 |
| Whittier | 87,306 |
| Alhambra | 82,868 |
| Lakewood | 82,496 |
| Bellflower | 79,190 |
| Baldwin Park | 72,176 |
| Redondo Beach | 71,576 |
| Lynwood | 67,265 |
| Montebello | 62,640 |
| Pico Rivera | 62,088 |
| Florence-Graham | 61,983 |
| Monterey Park | 61,096 |
| Gardena | 61,027 |
| Arcadia | 56,681 |
| South Whittier | 56,415 |
| Diamond Bar | 55,072 |
| Huntington Park | 54,883 |
| Hacienda Heights | 54,191 |
| Paramount | 53,733 |
| Glendora | 52,558 |
| Covina | 51,268 |
| Rosemead | 51,185 |
| Azusa | 50,000 |
| Cerritos | 49,578 |
| Rowland Heights | 48,231 |
| La Mirada | 48,008 |
| Altadena | 42,846 |
| Rancho Palos Verdes | 42,287 |
| Culver City | 40,779 |
| San Gabriel | 39,568 |
| Bell Gardens | 39,501 |
| La Puente | 38,062 |
| Monrovia | 37,931 |
| Claremont | 37,266 |
| Temple City | 36,494 |
| West Hollywood | 35,757 |
| Manhattan Beach | 35,506 |
| San Dimas | 34,924 |
| Westmont | 33,913 |
| Bell | 33,559 |
| Beverly Hills | 32,701 |
| Lawndale | 31,807 |
| La Verne | 31,334 |
| Walnut | 28,430 |
| South Pasadena | 26,943 |
| West Whittier-Los Nietos | 25,325 |
| Maywood | 25,138 |
| West Rancho Dominguez | 24,347 |
| Willowbrook | 24,295 |
| San Fernando | 23,946 |
| Calabasas | 23,241 |
| West Puente Valley | 22,959 |
| West Carson | 22,870 |
| Cudahy | 22,811 |
| East San Gabriel | 22,769 |
| Valinda | 22,437 |
| Duarte | 21,727 |
| Lomita | 20,921 |
| La Cañada Flintridge | 20,573 |
| Lennox | 20,323 |
| Agoura Hills | 20,299 |
| Stevenson Ranch | 20,178 |
| La Crescenta-Montrose | 19,997 |
| South San Jose Hills | 19,855 |
| Hermosa Beach | 19,728 |
| South El Monte | 19,567 |
| Santa Fe Springs | 19,219 |
| Castaic | 18,937 |
| El Segundo | 17,272 |
| Artesia | 16,395 |
| Vincent | 15,714 |
| Walnut Park | 15,214 |
| East Rancho Dominguez | 15,114 |
| Hawaiian Gardens | 14,149 |
| Palos Verdes Estates | 13,347 |
| Avocado Heights | 13,317 |
| Lake Los Angeles | 13,187 |
| San Marino | 12,513 |
| Commerce | 12,378 |
| Sun Village | 12,345 |
| Signal Hill | 11,848 |
| Quartz Hill | 11,447 |
| View Park-Windsor Hills | 11,419 |
| Marina del Rey | 11,373 |
| Sierra Madre | 11,268 |
| Malibu | 10,654 |
| East Whittier | 10,394 |
| Del Aire | 10,338 |
| Citrus | 10,243 |
| Charter Oak | 9,739 |
| West Athens | 9,393 |
| Alondra Park | 8,569 |
| Topanga | 8,560 |
| Rolling Hills Estates | 8,280 |
| Westlake Village | 8,029 |
| South San Gabriel | 7,920 |
| Acton | 7,431 |
| Ladera Heights | 6,654 |
| South Monrovia Island | 6,515 |
| East Pasadena | 6,021 |
| La Habra Heights | 5,682 |
| Mayflower Village | 5,402 |
| North El Monte | 3,730 |
| Avalon | 3,460 |
| Agua Dulce | 3,451 |
| Rose Hills | 2,927 |
| Desert View Highlands | 2,676 |
| Val Verde | 2,399 |
| San Pasqual | 2,101 |
| Rolling Hills | 1,739 |
| Hidden Hills | 1,725 |
| Elizabeth Lake | 1,651 |
| Leona Valley | 1,555 |
| Littlerock | 1,535 |
| Irwindale | 1,472 |
| Hasley Canyon | 1,195 |
| Green Valley | 1,036 |
| Bradbury | 921 |
| Lake Hughes | 544 |
| Industry | 264 |
| Vernon | 222 |
| First District | Hilda L. Solis |
| Second District | Holly J. Mitchell |
| Third District | Sheila Kuehl |
| Fourth District | Janice Hahn |
| Fifth District | Kathryn Barger |
In the United States House of Representatives, Los Angeles County is split between 18 congressional districts. In the California State Senate, Los Angeles County is split between 15 legislative districts. In the California State Assembly, Los Angeles County is split between 24 legislative districts.
On November 4, 2008, Los Angeles County was almost evenly split over Proposition 8, which amended the California Constitution to ban same-sex marriages. The county voted for the amendment 50.04% with a margin of 2,385 votes.
