In 1876, he was selected to serve as the Wyoming Territory's National Republican committeeman on the Republican National Committee and remained in the position until 1897. Mayor In 1880, Carey was elected as mayor of Cheyenne, Wyoming while he was out of state by running on a public works improvement platform. He was reelected in 1881, and again without opposition in 1882. During his tenure as mayor, the city's water and sewage systems were completed, an opera house was built, and the Stock Growers National Bank was organized and selected Carey to serve as its first president. The Wyoming Development Company was founded in 1883 with the intention of bringing water to thousands of arid acres of land in the Wheatland Flats. In 1885, Carey was selected to lead the organization and built a reservoir using water from the Laramie River. Water from the reservoir was transferred throughout the flats through canals and ditches and successfully irrigated 50,000 acres of land, allowing the area to become inhabitable. U.S. House of Representatives On July 30, 1874, the Wyoming Republican Party unanimously nominated Carey at its state convention to serve as the territory's delegate to the United States House of Representatives from the at-large congressional district, but was narrowly defeated by incumbent Democratic Delegate William Randolph Steele. On October 22, 1884, Carey was given the Republican nomination for the at-large congressional district after Francis E. Warren declined the nomination. In the general election, he defeated Democratic nominee William H. Holliday. During the 1884 election, the Wyoming Democratic Party did not nominate a candidate for the at-large congressional district and Carey received almost ninety percent of the popular vote with the remainder being split among Democratic write-in candidates. On October 8, 1888, he received the Republican nomination again and was reelected against Democratic nominee Caleb P. Organ. On May 18, 1887, he gave a speech at the dedication ceremony of the Wyoming State Capitol building. When Territorial Governor William Hale died, Carey asked President Chester A. Arthur to nominate Warren, as he was a resident of Wyoming, rather than select a non-resident. Warren was nominated and the rest of Wyoming's territorial governors until statehood were residents of Wyoming. President Benjamin Harrison offered to appoint Carey to an important position in Wyoming, but he declined as he wanted to work towards Wyoming statehood. In 1889, Carey proposed legislation that would admit Wyoming as a