county, southern tip of Nevada, U.S., wedged between California and Arizona. The county seat is Las Vegas, the internationally famous gaming and entertainment city. The broad desert valleys crisscrossed by mountains of the McCullough, Spring, Newberry, and Sheep ranges also include the cities of North Las Vegas, Henderson, and Boulder City.

Clark county was created in 1908. The county began to grow after completion of Hoover Dam (1936) on the Colorado River and grew dramatically after the first of many Las Vegas casinos (the Flamingo) was built in 1945. The county's population grew from 4,859 in 1920 to 48,289 in 1950 and to 463,087 in 1980.

Most employment is related to the gaming and tourist industry. In the northwest corner of the county are parts of the vast Nevada gunnery and air force ranges. Area 7,911 square miles (20,489 square km). Pop. (2000) 1,375,765; (2007 est.) 1,836,333.