Early life and education
Stevens was born in Danville, Vermont, on April 4, 1792. He was the second of four children, all boys, and was named to honor the Polish general who served in the American Revolution, Thaddeus Kościuszko. His parents were Baptists who had emigrated from Massachusetts around 1786. Thaddeus was born with a club foot, at the time seen as a judgment from God for secret parental sin—and his older brother was born with the condition in both feet. The boys' father, Joshua Stevens, was a farmer and cobbler who struggled to make a living in Vermont. After fathering two more sons (born without disability) Joshua abandoned the children and his wife Sarah (née Morrill). The circumstances of his departure, and his subsequent fate, are uncertain; he may have died at the Battle of Oswego during the War of 1812.
Sarah Stevens struggled to make a living from the farm, with the increasing aid of her sons. She was determined that her sons improve themselves, and in 1807 moved the family to the neighboring town of Peacham, where she enrolled young Thaddeus in the Caledonia Grammar School (often called the Peacham Academy). He suffered much from the taunts of his classmates for his disability. Later accounts describe him there as "wilful, headstrong" with "an overwhelming burning desire to secure an education".
After graduation in 1811, Stevens enrolled in the sophomore class at Dartmouth College in Hanover, New Hampshire. He spent his second year at Burlington College in Burlington, Vermont (today the University of Vermont) but had to return to New Hampshire when the Vermont school's campus was taken over by the federal government during the War of 1812. At Dartmouth, despite a stellar academic career, he was not elected to Phi Beta Kappa; this was said to have been a scarring experience for him.
Stevens graduated from Dartmouth in 1814, speaking at graduation. Afterwards, he returned to Peacham and briefly taught there. Stevens also began to study law with Judge John Mattocks in Danville. In early 1815, after writing to friends in York, Pennsylvania, he moved there.