Unlike the North Pacific Coast, Las Vegas is not a land of trees. Moreover, the closest national park to Las Vegas is the Great Basin. The Great Basin includes valleys, basins, lakes, and mountain ranges of Basin and Range topography. The Great Basin almost entirely contains the smaller Great Basin physiographic section, which extends about 10,000 sq mi (26,000 km2) into the Colorado River watershed (including the Las Vegas metropolitan area and northwest corner of Arizona).
Source:
http://en.wikipedia.org/wiki/Great_Basin