Thomas Allen was born on August 29, 1813 at Pittsfield, Massachusetts, United States. He was the son of Jonathan and Eunice (Larned) Allen. His father was a member of both houses of the Massachusetts legislature; through his grandmother he was a descendant of William Bradford.
Allen graduated from Union College in 1832. Later he studied law in an office in New York City, supporting himself by writing for the Family Magazine.
Allen was admitted to the bar in 1835. But he never practised law actively. In 1837 he started at Washington the Madisonian, an anti-Van Buren Democratic paper, which supported Harrison in 1840. The Madisonian was to be the organ of the new administration, but on Harrison's death Allen sold the paper and in 1842 removed to St. Louis.
His real career began in 1848-1849, when he was a prime mover in the National Railroad Convention at St. Louis, writing the preliminary publicity, the memorial to Congress, and the address to the public. In 1850 was elected to the state Senate. Here he was largely responsible for the initiation of the policy of state loans to the railroads, securing a loan of two million dollars for the Pacific road; his elaborate report of 1852 was later very closely followed and was the basis of the earlier railroad system of the state.
In 1854 he resigned the presidency of the Pacific Railroad, which he had held since 1851, and withdrew from politics.
In 1858 he organized the banking-house of Allen, Copp & Nisbet. When at the close of the war the bankrupt, state-aided railroads were reorganized, Allen purchased the Iron Mountain, then eighty-six miles in length, and by further purchases and the construction of a hundred miles a year built up by 1874 the St. Louis, Iron Mountain & Southern system of 686 miles. He retained control of it until he sold out to Jay Gould in 1881. He was also interested in the St. Louis street-railway developments. Save for an unsuccessful campaign for Congress in 1862 on the Union ticket, he had taken no active part in politics for many years, but in 1880 he was elected to Congress on the Democratic ticket.
He died in Washington on April 8, 1882.
Allen was a member of the Democratic party.
Allen was a man of definite objectives, strict standards of personal conduct, great force and determination.
Allen was married in 1842 to Ann Russell, the daughter of William Russell of St. Louis. They had ten children; two of them died in childhood.
