Born in Easton, Talbot County, Maryland. Graduate of Dickinson College in 1830. Admitted to Maryland bar in 1831. Married Sarah Maria Kerr February 5, 1835. Married Clintonia Wright May on January 29, 1876. Thomas had 13 children.

Elected to Maryland House of Delegates 1838. Served in U.S. House of Representatives March 4, 1839, to March 3, 1841, and again March 4, 1875, to March 3, 1877. Elected Governor of Maryland and served 1848 to 1851.

Served as Comptroller of the U.S. Treasury 1851 to 1853. Appointed Secretary of the Treasury by President Buchanan and served December 12, 1860, to January 14, 1861.

Thomas was elected to the U.S. Senate in 1867 but was denied his seat on a charge of disloyalty. He resumed the practice of law in Maryland. He died in Baltimore, Maryland.

bio: ApCAB; BDC; BDEB; DAB; Drake; NCAB 5; TCBDA; WWWA-H