Whittlesey was elected to the Eighteenth through Twenty-second Congresses, elected as an Anti-Masonic candidate to the Twenty-third Congress, and elected as a Whig to the Twenty-fourth and Twenty-fifth Congresses and served from March 4, 1823, to July 9, 1838, when he resigned. He was one of the founders of the Whig Party.
He served as chairman of the Committee on Claims (Twenty-first through Twenty-fifth Congresses).
He was Sixth Auditor of the Treasury from March 18, 1841, until December 18, 1843,[1] when he resigned and resumed the practice of law in Canfield.
He was appointed general agent of the Washington Monument Association in 1847.
He was appointed by President Zachary Taylor as First Comptroller of the Treasury and served from May 31, 1849, to March 26, 1857, when he was removed by President James Buchanan.[2]
He was reappointed by President Abraham Lincoln April 10, 1861, and served until his death in Washington, D.C., January 7, 1863. He was interred in the Canfield Village Cemetery, Canfield, Ohio.
