Sweat attended Bowdoin College, from which he graduated in 1837, and studied law with Rufus McIntire.

[1] Sweat returned to Maine and settled in Portland, where he continued to practice law.

[1] In 1849, he married novelist Margaret Jane Mussey and purchased a home adjoining author and critic, John Neal.

[3] Sweat held various local offices including Portland City Solicitor from 1856 to 1860.

[citation needed] He was an honorary commissioner to the World's Exposition in Paris in 1867 and that in Vienna in 1873.