Following the Civil War, Warren engaged in
farming and stock-raising in Massachusetts before moving to Wyoming (then part of the
Territory of Dakota) in 1868. Settling in
Cheyenne, Warren engaged in
real estate,
mercantile business,
livestock raising and the establishment of Cheyenne's
first lighting system, becoming quite wealthy. Warren's political work included: member, Wyoming
Territorial Senate (1873–1874, 1884–1885), serving as senate president; member, Cheyenne
City Council (1873–1874);
treasurer of Wyoming (1876, 1879, 1882, 1884); and
Mayor of Cheyenne (1885). In February 1885, Warren was appointed
Governor of the
Territory of Wyoming by President
Chester A. Arthur, although he was removed by
Democratic President
Grover Cleveland in November 1886. He was reappointed by President
Benjamin Harrison in April 1889, and served until 1890, when he was elected first
Governor of Wyoming (October 11, 1890 – November 24, 1890). ==Senate years and death==