About 13 percent of U.S. cropland was irrigated in 1982, contributing almost 32 percent of the total value of crops produced. This study describes some of the principal features of the irrigated sector in U.S. agriculture, using data for 1974, 1978, 1982, and 1984. The predominant irrigation States continue to be those in the Pacific and Mountain regions and the Great Plains areas. Irrigation is growing very rapidly in other regions, particularly the Lake States and Corn Belt regions. In the Southern Plains, irrigation since 1974 has declined by about 14 percent. As of 1984, about 60 percent of all irrigation systems were gravity flow, with the balance either sprinkler or drip systems.