Following the American Civil War, he resumed the practice of law and also engaged in railroad building, at which he gained significant success and wealth.

In 1845 he called a convention to form an independent movement in favor of anti-slavery Congressional Candidate John P. Hale.

After three consecutive terms he returned to Exeter in 1853 and began a movement to unite the many minor political factions that existed in the state of New Hampshire.

Tuck organized a secret meeting, on October 12, 1853, at Major Blake's Hotel in Exeter of a group of anti-slavery men.

Tuck was appointed a delegate to the peace convention held in Washington, D.C., in 1861 in an effort to devise means to prevent the impending war.

He was a personal friend of Abraham Lincoln, John Greenleaf Whittier and many other men prominent in his time.

His son, Edward Tuck, financed and founded at Dartmouth College the Amos Tuck School of Business Administration, and funded the New Hampshire Historical Society building, a beautiful granite structure in Concord, New Hampshire.