 In the years following his Army service, Johnson became a contractor for railroad construction.He was a member of the New York State Senate (26th D.) from 1872 to 1875, sitting in the 95th, 96th, 97th and 98th New York State Legislatures.He was elected to the New York State Senate in the fall of 1871, as a Democrat representing the 26th District, then comprising Ontario, Seneca, and Yates counties.