The USGS Central Region Energy Team assesses oil and gas resources of the United States. The onshore and State water areas of the United States comprise 71 provinces. Within these provinces, Total Petroleum Systems are defined and Assessment Units are defined and assessed. Each of these provinces is defined geologically, and most province boundaries are defined by major geologic changes. The Eastern Great Basin Province is located in western Utah, eastern Nevada, southern Idaho, and the northwest corner of Arizona, encompassing all or parts of Mohave County in Arizona, Power, Bannock, Cassia, Oneida, and Franklin Counties in Idaho, Elko, Eureka, Lander, White Pine, Nye, Lincoln, and Clark Counties in Nevada, and Cache, Box Elder, Weber, Davis, Tooele, Salt Lake, Wasatch, Utah, Juab, Sanpete, Millard, Sevier, Beaver, Piute, Iron, and Washington Counties in Utah. The main population centers within the study area are Henderson and Las Vegas, Nevada.; Provo and Salt Lake City, Utah. The main highways, I-80, U.S. 6 and U.S. 50, generally traverse the area from east to west; I-15 travels northeast/southwest on the eastern portion of Eastern Great Basin from Salt Lake City, Utah to Las Vegas, Nevada. The Sevier River, Humboldt River, and Colorado River and their tributaries drain the area. The province boundary was drawn to include the geologic structures generally considered to be in or bounding the eastern portion of the Great Basin.