After a peace treaty between Mexico and the United States was signed in 1849, Congress was petitioned to admit the State of Desert to the Union, but the petition was denied and the Organic Act of September 9, 1850, created the Utah Territory. On October 4, 1851, under the direction of Governor Brigham Young, the Utah Territorial Legislature created Millard County and designated Fillmore as both the county seat and the capitol of the Territory because of its central location. Fillmore and Millard County were named after the 13th President of the United States, Millard Fillmore, because of his friendship to the Mormon people. To carry out this plan, a capitol building was designed and construction began in the spring of 1852. The new Statehouse was intended to be a four-winged structure with a large central dome, but because of financial difficulties and other factors, only one wing was completed. After one complete session of the Territorial Legislature in 1855-1856 and two partial sessions, the Territorial Capitol was moved to Salt Lake City. The old Territorial Capitol building survives in the center of Fillmore as a preserved state park history museum, and the legacy of these early pioneers remains visible in many cities and towns, homes, and shops.