[7] The county's seat, Los Angeles, is the second most populous city in the United States, with 3,820,914 residents estimated in 2023.

[14] Los Angeles County borders 70 miles (110 km) of coast on the Pacific Ocean and encompasses mountain ranges, valleys, forests, islands, lakes, rivers, and desert.

The western extent of the Mojave Desert begins in the Antelope Valley, in the northeastern part of the county.

The county is divided west-to-east by the San Gabriel Mountains, which are part of the Transverse Ranges of southern California, and are contained mostly within the Angeles National Forest.

[28] Hispanic or Latino residents of any race numbered 4,687,889 (48%); 36% of Los Angeles County's population was of Mexican ancestry, 3.7% Salvadoran, and 2.2% Guatemalan heritage.

[29] The county has a large population of Asian Americans, being home to the largest numbers of Burmese, Cambodian, Chinese, Filipino, Indonesian, Korean, Sri Lankan, Taiwanese, and Thai outside their respective countries.

[30] The largest Asian groups in Los Angeles County are 4.0% Chinese, 3.3% Filipino, 2.2% Korean, 1.0% Japanese, 0.9% Vietnamese, 0.8% Indian, and 0.3% Cambodian.

45.9% of the population reported speaking only English at home; 37.9% spoke Spanish, 2.22% Tagalog, 2.0% Chinese, 1.9% Korean, 1.87% Armenian, 0.5% Arabic, and 0.2% Hindi.

[56] The Roman Catholic Archdiocese of Los Angeles has approximately 5 million members and is the largest diocese in the United States.

As a quasi-judicial body, the Board is the final venue of appeal in the local planning process, and holds public hearings on various agenda items.

In the United States House of Representatives, Los Angeles County is split between 17 congressional districts.

[67] On November 4, 2008, Los Angeles County was almost evenly split over Proposition 8, which amended the California Constitution to ban same-sex marriages.

Historically, the courthouses were county-owned buildings that were maintained at county expense, which created significant friction since the trial court judges, as officials of the state government, had to lobby the county Board of Supervisors for facility renovations and upgrades.

State cases are appealed to the Court of Appeal for the Second Appellate District, which is also headquartered in the Civic Center, and then to the California Supreme Court, which is headquartered in San Francisco but also hears argument in Los Angeles (again, in the Civic Center).

Crime in 2013 According to the authors of Wild L.A., a book about urban biodiversity, "Los Angeles is the birdiest county in the country with over 500 recorded species."

LA's amenable climate supports a large number of introduced, tropical and migratory species.

[76] The range of habitats in the county is "greater than in many states, with mountains, wetlands, desert, ocean, meadows and chaparral, each with its own endemic species.

[78] Charismatic biodiversity indicator species native to the area include three species of amphibian (Baja California chorus frog, black-bellied slender salamander, western toad), 14 species of bird (acorn woodpecker, California quail, canyon wren, cinnamon teal, great blue heron, great horned owl, greater roadrunner, hooded merganser, Northern harrier, red-tailed hawk, red-winged blackbird, spotted towhee, western bluebird, western meadowlark), nine kinds of invertebrates (Behr's metalmark, bramble green hairstreak, bumblebees, El Segundo blue butterfly, harvester ants, Lorquin's admiral, North American Jerusalem crickets, Sara orangetip, velvet ants), five mammals (bobcat, dusky footed woodrat, gray fox, mountain lion, mule deer), and six reptiles (California kingsnake, coachwhip snake, gopher snake, side-blotched lizard, western pond turtle, western rattlesnake).

[79] Any observations of these species within the county are considered ecologically significant indicators of ecosystem health and may be documented using the iNaturalist app.

[84][85] Despite a business exodus from Downtown Los Angeles since the COVID-19 pandemic, the city's urban core is evolving as a cultural center with the world's largest showcase of architecture designed by Frank Gehry.

Santa Monica's pier is a well known tourist spot, famous for its Ferris wheel and bumper car rides, which were featured in the introductory segment of the television sitcom Three's Company.

Mount Wilson Observatory in the San Gabriel Mountains is open for the public to view astronomical stars from its telescope, now computer-assisted.

The California Poppy Reserve is located in the western Antelope Valley and shows off the State's flower in great quantity on its rolling hills every spring.

Amtrak has the following intercity Amtrak service at Union Station in the city of Los Angeles: Union Station is also the primary hub for Metrolink commuter rail, which serves much of the Greater Los Angeles Area.

The Port of Los Angeles is the largest cruise ship center on the West Coast, handling more than 1 million passengers annually.