Lake Mead - a large reservoir in southeastern Nevada and northwestern Arizona that is formed by the Hoover Dam on the Colorado River; the center of a recreational area

Grand Canyon National Park - a national park in Arizona including the mile deep canyon of the Colorado River which shows geologic features and fossil plants and animals

Petrified Forest National Park - a national park in Arizona having the world's largest collection of petrified coniferous trees

American state - one of the 50 states of the United States

U.S.A., United States, United States of America, US, USA, America, U.S. - North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776

Flagstaff - a town in north central Arizona; site of an important observatory

Mesa - a city just east of Phoenix; originally a suburb of Phoenix

Nogales - a town in Arizona on the Mexican border opposite Nogales, Mexico

capital of Arizona, Phoenix - the state capital and largest city of Arizona; situated in a former desert that has become a prosperous agricultural center thanks to irrigation

Prescott - a town in central Arizona

Tucson - a city in southeastern Arizona ringed by mountain ranges; long known as a winter and health resort but the population shift from industrial states to the Sunbelt resulted in rapid growth late in the 20th century

Yuma - a town in southwestern Arizona on the Colorado River and the California border

Gila Desert - a desert area in southern Arizona

Painted Desert - a desert on a high plateau in northeastern Arizona

Sonoran Desert - a desert in southwestern Arizona

Cataract Canyon - a tributary of the Grand Canyon

Colorado River, Colorado - a river in southwestern United States; rises in the Rocky Mountains of northern Colorado and flows southwest through Utah into Arizona (where it flows through the Grand Canyon) and then southward forming the border between California and Arizona and finally into Mexico where it empties into the Gulf of California; an important source of water in the southwestern United States

Colorado Plateau - a large plateau south and west of the Rocky Mountains; abuts mountains on the north and east and ends in an escarpment overlooking lowlands to the south and west; the Grand Canyon is carved out of the southwestern corner

Gila, Gila River - a river that rises in western New Mexico and flows westward through southern Arizona to become a tributary of the Colorado River

Grand Canyon - the enormous gorge of the Colorado River in northern Arizona

reptile genus - a genus of reptiles

Colubridae, family Colubridae - nonvenomous snakes; about two-thirds of all living species

Arizona elegans, glossy snake - nocturnal burrowing snake of western United States with shiny tan scales