Box Elder County The county was created by the Utah Territory legislature on January 5, 1856, with the territory partitioned from Weber County. Its boundaries were altered in 1862 by adjustments between counties and in 1866 when all its area in the now-existent state of Nevada (which had gained territorial status in 1861 and statehood in 1864) was formally partitioned. The county boundaries were finally altered in 1880 by adjustments between Salt Lake and Weber counties. Its boundary has remained unchanged since 1880.
The California Trail followed Goose Creek from a point just north of the Idaho/Utah border southwest across northwestern Box Elder County to Little Goose Creek in northeastern Elko County, Nevada. The link-up of the first transcontinental railroad occurred at Promontory Summit, Utah in 1869.
The Spiral Jetty, an earthwork sculpture by Robert Smithson, was built on the north shore of the Great Salt Lake in Box Elder County in 1970. On November 19, 2005, sculptor Zaq Landsberg declared his plot to be independent from the US, creating the Republic of Zaqistan