 Born in Perryville, Maryland, Thomas attended private schools and graduated from the University of Pennsylvania at Philadelphia in 1783.He moved to "Fairland" in Anne Arundel County, Maryland, around 1789, studied law, and was admitted to the bar in Philadelphia on December 15, 1787 but did not engage in extensive practice.He was elected as a Federalist to the Sixth Congress, and served from March 4, 1799 to March 3, 1801, but declined to be a candidate for reelection in 1800.