Area: 5,614 square miles; population: 36,485 (in 1990); county seat: Brigham City; origin of county name: named for the many box elder trees growing there; principal cities/towns: Brigham City (15,644), Tremonton (4,264), Garland (1,637), Willard (1,298), Perry (1,211), Honeyville (1,112), Bear River City (700), Clarkston (645), Corinne (639); economy: agriculture, aerospace/defense; points of interest: Willard Bay, Crystal Hot Springs, Brigham City Museum and Gallery, Golden Spike National Historic Site, Box Elder LDS Tabernacle in Brigham City, Willard Historic District, Bear River Migratory Bird Refuge.

Located in the upper northwest corner of the state of Utah, Box Elder County is part of the Great Basin region and embraces a large land area extending from the west spur of the Wasatch Mountains to the Idaho border and westward to Nevada. It includes portions of the Great Salt Lake and the Great Salt Lake Desert. On the east are the lower course and deltas of the Bear River, the Malad River Valley, and the Promontory Mountains. Diverse in topography, the county contains rich farmlands as well as extensive marshlands at the mouth of the Bear River.

Prehistoric big-game hunters seeking mammoths, camels, and bison roamed the area as early as 12,000 years ago, as did Indians of the later Plains Culture. Danger Cave, Promontory Caves, Hogup Cave, and Shallow Shelter are among the important archaeological sites found in Box Elder County. During the 1820s and 1830s fur trappers, including Peter Skene Ogden and Joseph R. Walker, explored the eastern and northern parts of the county. Permanent white settlement began in 1851 when a group of Mormons took up land in North Willow Creek (Willard). Brigham City was settled that year. Because the land was already inhabited by Shoshoni Indians, livestock raids and violent clashes between Indians and settlers were common until Territorial Governor James Duane Doty negotiated the Treaty of Box Elder on 30 July 1863 in Brigham City.

In 1856 the territorial legislature created Box Elder County from part of Weber County. Its boundaries were redefined in 1880 when the legislature divided the water and islands of the Great Salt Lake among Salt Lake, Davis, Weber, Tooele, and Box Elder counties.

The most significant event in Box Elder County history took place on 10 May 1869 at Promontory when the driving of the Golden Spike joined the Central Pacific and the Union Pacific railroads to complete the transcontinental line. Corinne, a feisty, non-Mormon boomtown, became the freight transfer point for goods shipped to Idaho and Montana. In July 1870 Corinne residents spurred the founding of the Liberal party to oppose the Mormons' People's party.

Agriculture has always played an important role in the economy of Box Elder County. Some 43 percent of the county's land is used for agricultural purposes. Besides the standard crops of hay, grain, and alfalfa, beginning in 1901 sugar beets were also raised, and kept two sugar factories, one in Garland and the other in Brigham City, operating for many years. Abundant fruit orchards and garden crops continue to contribute to the local economy. Since 1957, when Thiokol Chemical (now Morton-Thiokol) began its Brigham City operation, defense and aerospace have dominated the local economy and presently employ some 5,000 people. Morton-Thiokol built the Minuteman missile and the space shuttle booster rockets.