Las Vegas is situated within Clark County in an arid basin on the desert floor, surrounded by dry mountains. The Spring Mountains lie to the west. Much of the landscape is rocky and dusty; the environment is dominated by desert vegetation and some wildlife, and the area is subject to torrential flash floods. The elevation is around 2,030 ft (620 m) above sea level. According to the United States Census Bureau, the city has a total area of 135.86 sq mi (351.9 km²), of which 131.81 sq mi (341.4 km²) is land and 0.05 sq mi (0.13 km²) (0.03%) is water.

Within the city there are many lawns, trees, and other greenery. Due to water resource issues, there is now a movement to encourage xeriscapes. Another part of the water conservation efforts include scheduled watering groups for watering residential landscaping. A U.S. Environmental Protection Agency grant in 2008 funded a program that analyzed and forecast growth and environmental impacts through the year 2019. This study resulted in an expansion of the sewage treatment capacity, which enabled rapid population growth.