Yuma County was one of the original four counties designated by the first Territorial Legislature. Until 1983, when voters decided to split it into La Paz County in the north and a new Yuma County in the south, it maintained its original boundaries.

In 1540, just 48 years after Columbus arrived in America, 18 years after the conquest of Mexico by Cortéz, and 67 years before the settlement of Jamestown, Hernando de Alarcón visited the site of what is now the city of Yuma. He was the first European to set foot in the area and to recognize the best natural crossing of the Colorado River.

From the 1850s through the 1870s, steamboats on the Colorado River transported passengers and goods to mines, ranches and military outposts in the area, serving the ports of Yuma, Laguna, Castle Dome, Norton’s Landing, Ehrenberg, Aubry, Ft. Mohave and Hardyville.

For many years, Yuma served as the gateway to the new western territory of California. In 1870, the Southern Pacific Railroad bridged the river, and Yuma became a hub for the railroad and was selected as the county seat.

Much of Yuma County’s 5,519 square miles is desert land accented by rugged mountains. The valley regions, however, contain an abundance of arable land, which is irrigated with Colorado River water. Agriculture, tourism, military and government are the county’s principal industries. During the winter months, the population grows considerably with part-time residents.

The U.S. Bureau of Land Management accounts for 14 percent of land ownership; Indian reservations, less than 0.5 percent; the state of Arizona, 5 percent; individual or corporate, 11 percent; and other public lands, 70 percent, including the U.S. Department of Defense and the U.S. Fish and Wildlife Service.