Alston claims to have visited the Princeton College, but there are no official record of it. He also went to agricultural work. In 1790 he was elected to the House of Representatives from North Carolina, where he remained two years. He was then elected in 1794 for a term in the Senate of North Carolina.
1798 Alston was elected as a Federalist to the U.S. House of Representatives; thereby defeating the predecessor Thomas Blount and two other candidates. He remained there on 4 March 1799 to 3 March 1816. At the beginning of Jefferson's term as U.S. President, he joined the Party and the Democratic Republicans joined them. Then promoted the Federalists in 1803 the former Governor William Richardson Davie and set it up as Alston's challenger, but without success. During his time in Congress, he had presided over the House Committee on Revisal and Unfinished Business ( 13th Congress ). In the election in April 1813, he defeated the challenger Daniel Mason, the candidate of the short-lived Peace Party, with the smallest margin ( 56% to 44%) in all his re- election. Alston retired after the end of the term.
Thereafter, he was elected again in the House of Representatives from North Carolina, where he served from 1820 to 1824. He was then selected as the 1825 Jackson Democrat in Congress and confirmed two more times. He was there from March 4, 1825 until March 3, 1831 worked at the end then as a Democrat. During this time he had presided over the Committee on Elections ( 21 Congress ). He decided in 1830 against a re-election and went his farm work after.