 In 1879 he was elected as an alderman of the City of Waupaca.In 1884, when J. H. Woodnorth (Mumbrue’s former partner in dry goods) was appointed register of the United States Land Office at Menasha, Wisconsin, Mumbrue was appointed Woodnorth's deputy, and served four years.He was confirmed in 1893 (under Democratic President Grover Cleveland, newly returned to office) as postmaster in Waupaca and as of 1896 was in office at a salary of $1,600 "per annum"., but was replaced after the 1896 presidential election brought McKinley supporters into power by Adelbert Penney, who had bought Mumbrue's old house on Main Street in 1890.