Zihlman served as a member of the
Maryland State Senate from 1909 to 1917, serving as Republican floor leader in 1914 and 1916. He was an unsuccessful candidate for election in 1914 to the Sixty-fourth US Congress, but was elected two years later as a Republican to the Sixty-fifth and to the six succeeding Congresses, serving from March 4, 1917, to March 3, 1931. In Congress, Zihlman was chairman of the
Committee on Expenditures in the Post Office Department (Sixty-sixth and Sixty-seventh Congresses). Zihlman was the only Representative from Maryland to vote for the
Dyer Anti-Lynching Bill. He was also a member of the
Committee on the District of Columbia (Sixty-seventh Congress and Sixty-ninth through Seventy-first Congresses) and the
Committee on Labor (Sixty-seventh and Sixty-eighth Congresses). Zihlman was accused of corruption and bribery in 1929. When the inquiry produced no evidence, he was acquitted.{{cite news | work = The Baltimore Sun After his tenure in Congress, he resumed his former business pursuits in Cumberland, until his death there. He is interred in St. John's Cemetery in
Forest Glen, Maryland. ==References==