

Additionally, bedrock of sedimentary sandstone, igneous granodiorite, and metamorphic gneiss also cover significant areas of LA County. Most of LA County is dominated by alluvium in the lowlands areas of the LA and Mojave basins. LA County’s varied geology has created diverse topographic, climate, and vegetation conditions in the region that plants and animals have evolved and adapted to over countless generations. Meanwhile number three Harris County, Texas (home to Houston) and number four Maricopa County, Arizona (home to Phoenix) have just 4.7 and 4.4 million residents, respectively. The second largest county in the country is Cook County, Illinois (home to the city of Chicago), which has 5.3 million residents. Interestingly, Los Angeles County is the most populous county in the United States by a sizable amount. Other major population centers in the county include the Santa Clarita Valley, Pomona Valley, Crescenta Valley, and Antelope Valley. While many of LA County’s 10 million residents reside in the city of Los Angeles in the Los Angeles Basin, many also reside in the San Fernando Valley and San Gabriel Valley. All in all, LA County is home to 3 major protected areas: Angeles National Forest, Los Padres National Forest (most of which is in Ventura County and Santa Barbara County), and the Santa Monica Mountains National Recreation Area. The western extent of the Mojave Desert begins in the Antelope Valley in the northeastern part of LA County. The county’s primary mountain ranges are the Santa Monica Mountains and the San Gabriel Mountains, which are home to hundreds of miles of trails and dozens of mountain summits.

Los Angeles County also includes San Clemente Island and Santa Catalina Island in the Channel Islands archipelago off the Pacific Coast. LA County is located to the east of Ventura County, to the south of Kern County, to the west of San Bernardino County, and to the north of Orange County. LA County has 70 miles (110 km) of Pacific Ocean coastline and is home to a vast array of mountain ranges, valleys, forests, islands, lakes, rivers, and desert. km) of land and 693 square miles (1,790 sq. The county encompasses an area of 4,751 square miles (12,310 sq. The county is home to more than 600 parks, over 550 miles (885 km) of trails, and hundreds of mountain peaks in the San Gabriel Mountains, Sierra Pelona Mountains, Santa Monica Mountains, and Santa Susana Mountains. Los Angeles County (LA County) is an administrative region located in the southern part of the US state of California.
