Poppleton served in many political roles in pioneer Omaha. One of the founders of the
Omaha Claim Club, Poppleton was also heavily involved in the enforcement of its rules over the city. When the club went to the
U.S. Supreme Court, it was Poppleton who mounted the defense. They lost. Poppleton was a member of the
Nebraska Territorial Legislature in 1854–55 and 1857–58. In a fluke in 1857, Poppleton served as the Speaker of the House of Representatives in the
Nebraska Territorial Legislature. After that, he was the second mayor of young Omaha, serving for six months from March 2, 1858, until September 14, 1858, when he resigned from office. Poppleton was afterwards an influential
real estate businessman and
lawyer in Omaha. Poppleton worked for many years as the general attorney for the
Union Pacific Railroad. The most important case he ever argued was the 1879 trial of
Standing Bear v. Crook, held at
Fort Omaha. Poppleton, and noted Omaha lawyer
John Lee Webster, argued in
U.S. District Court that Native Americans such as Standing Bear, a
Ponca chief, are "persons within the meaning of the law" and have the rights of citizenship. ==Personal life==