Area: 6,923 square miles; population: 26,601 (in 1990); county seat: Tooele City; origin of county name: probably from tule, a Spanish word of Aztec origin, meaning bulrush, a marsh plant; principal cities/towns: Tooele City (13,887), Grantsville (4,500), Wendover (1,122); economy: defense, transportation, communications, trade, services; points of interest: Bonneville Speedway, Deseret Peak Wilderness Area, Ophir Town Hall, Grantsville First Ward, Old Pony Express and Stage Route, Iosepa Cemetery, Great Salt Lake.

Tooele County is Basin and Range country. Most of its towns lie in a broad valley between the mineral-rich Oquirrh Mountains on the eastern border and the Onaqui and Stansbury mountains to the west. The Great Salt Lake Desert covers most of western Tooele County, except the southwest corner where the Deep Creek Mountains rise.

Prehistoric Indian sites have been discovered in the county, but it is the Goshutes, a branch of the Western Shoshone, who claim this harsh environment as their ancestral homeland. Their ingenious use of the limited plant and animal resources of the area amazed the first white travelers. The Goshutes currently have a reservation in Skull Valley.

Tuilla, as it was originally spelled, was one of six counties created in January 1850. Its boundaries were changed a number of times before it achieved its present size as the state's second largest county.

The Mormons herded livestock in Tooele Valley before permanent settlement began in 1849. The early settlers farmed, built gristmills and sawmills, and manufactured salt, charcoal, lime, adobe bricks, and woolen products. Large sheep and cattle herds were developed, and hay and grain became important crops. But mining and smelting, not agriculture, led the county's growth from the 1860s to World War II.