McCook returned to Steubenville following the war and was admitted to the bar in 1866. He served as the U.S. assessor of internal revenue taxes from November 1865 until May 1873, when he moved to
New York City, established a law practice, and entered politics. He was the founder and editor of the
Daily Register (later known as the
New York Law Journal). He served as president of the New York Law Publishing Company until his death. He became close friends with several leading
Republicans, including former comrades in arms
James Garfield,
Rutherford B. Hayes, and Ohio Senator
John Sherman. McCook was elected to the
United States House of Representatives in the
Forty-fifth Congress as a delegate from
Lower Manhattan, and served from 1877 until 1883. He was defeated for a fourth term in the elections of 1882. Among his duties was serving on the House committee that oversaw military affairs. In December 1883, the Republican Caucus elected McCook as the
Secretary of the United States Senate, a post he held until 1893 when the
Democrats regained control of the Senate and replaced him with former Confederate general
William Ruffin Cox. McCook adopted an employee merit system and resisted senators' strong and persistent pressures for patronage appointments. He modernized office procedures and instituted a program for preserving the Senate's historical archives. Mayor
William L. Strong appointed McCook as city chamberlain of the city of New York and he served in that capacity from 1895 to 1898, as well as continuing to run his publishing company. He died in New York City on December 30, 1917, and was buried in
Union Cemetery-Beatty Park in his native Steubenville. ==See also==