Production of crops, mainly wheat, and cattle raising are the mainstays of the economy. Mineral resources are largely restricted to the western portions of the state and include oil, natural gas, and lignite coal. Because of the severity of the climate, sparse population, and distances to major markets, industrial development in North Dakota has been quite limited compared with other states. The amount of annual precipitation often varies greatly, resulting in alternating wet and dry periods. One aspect of special significance is the fact that about 77 percent of the average annual precipitation is received during the growing season.
Evaporation exceeds precipitation throughout North Dakota.
Evaporation rates are greatly influenced by the high winds, typical of the interior of North America and particularly of the Great Plains area. Physiography North Dakota lies at the center of the North American continent. It is crossed by a continental divide that separates the drainage system flowing to Hudson Bay from that terminating in the Gulf of Mexico. Elevations above sea level range from 790 feet in the northeastern corner to 3,506 feet at White Butte in the southwestern part. The predominant glacial landforms include lake plain, ground moraine, and dead-ice moraine.