 The county was created by the Utah Territory legislature on January 5, 1856, with 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.