|County of Los Angeles|
|— County —|
|County of Los Angeles|
|Map of Los Angeles County, with incorporated areas; inset- location of the county in California|
|California's location in the United States|
|Metro area||Los Angeles metropolitan area|
|Named for||Named for the city of Los Angeles|
|County seat||Los Angeles|
|- Chief Executive Officer||William T Fujioka|
|- Board of Supervisors|
|- Total|| dunams (
Expression error: Syntax error in line: 1 - Operator: * is no prefix operator. *0.001 round 1 ^km2 / 4752 sq mi)
|Population (2011 estimate)||11099059|
|- Urban density|
|- Rural density|
|- Metro density|
|Time zone||Pacific Standard Time (UTC-8)|
|- Summer (DST)||Pacific Daylight Time (UTC-7)|
|ZIP Code||90001-90899, 91001-93599|
|Area code(s)||213, 310, 323, 424, 562, 626, 661, 818|
Los Angeles County (incorporated as the County of Los Angeles) is a county in California and is the most populous county in the United States. Figures from the U.S. Census Bureau give an estimated 2009 population of 9,848,011 residents, while the California Department of Finance lists a July 1, 2010, estimate of 10,473,535. The county seat is the city of Los Angeles, the largest city in California and the second-largest city in the United States.
The county is home to 88 incorporated cities and many unincorporated areas. At , it is larger than combined areas of the states of Rhode Island and Delaware. The southern portion is the most heavily urbanized area and is home to the vast majority of the population which lives along the Southern California coastline and the inland basins and valleys. The northern half is a large expanse of less-populated desert including the Santa Clarita Valley and the Antelope Valley, which encompasses the northeastern part of the county and is adjacent to Kern County. In between these portions of the county sit the San Gabriel Mountains and the vast wilderness known as the Angeles National Forest.
The county is home to over a quarter of all California residents. One of the most diverse counties in the country, it holds most of the principal cities encompassing the Greater Los Angeles Area and is the core of the five counties that make up the area.
Los Angeles County was one of the original counties of California, created at the time of statehood in 1850. The county's large area included parts of what is now Kern County, San Bernardino County, Riverside County and Orange County. These parts of the county's territory were given to San Bernardino County in 1853, to Kern County in 1866 and to Orange County in 1889. In 1893, part of San Bernardino County became Riverside County.
With 4,061 square miles (10,517 km²), Los Angeles County borders of coast on the Pacific Ocean and encompasses numerous other natural landscapes including towering mountain ranges, deep valleys, forests, islands, lakes, rivers, and desert. The county contains the following rivers: Los Angeles River, Rio Hondo, the San Gabriel River and the Santa Clara River. The primary mountain ranges are the Santa Monica Mountains and the San Gabriel Mountains. It also includes the westernmost part of the Mojave Desert, and San Clemente Island and Santa Catalina Island in the Pacific Ocean.
Most of the population of Los Angeles County is located in the south and southwest. The major population centers are the Los Angeles Basin and the San Fernando and San Gabriel Valleys. Moderate populations are in the Santa Clarita, Crescenta and The Antelope Valley. The area north of the Santa Clarita Valley (Northwest Los Angeles County, adjacent to Ventura and Kern counties) is mostly mountainous, rugged, well-timbered and filled with coniferous forests that receives plentiful snow in the winter, right to the point of blizzard conditions. This area is less populated. Mountains in this area include San Emigdio Mountains, the southernmost part of Tehachapi Mountains, and the Sierra Pelona Mountains.
Most of the highest peaks in the county are located in the San Gabriel Mountains, which are part of the Transverse Ranges. They include Mount San Antonio (10,068 ft) at the Los Angeles-San Bernardino county lines, Mount Baden-Powell (9,399 ft), Mount Burnham (8,997 ft), and the well-known Mount Wilson (5,710 ft) where the Mount Wilson Observatory is located. Several smaller, lower peaks are located in the northern, western, and southwestern Los Angeles County.
The county has a total area of 4,752 square miles (12,308 km²), of which 4,061 square miles (10,518 km²) is land and 691 square miles (1,791 km²) (14.55%) is water.