Thornton was born in Ireland and was three years of age when his family immigrated over to the American colonies settling in Maine at first and then quickly moved to Massachusetts Bay Colony. He would later move to New Hampshire where he would become a physician and be appointed physician over the New Hampshire militia. He was elected as a New Hampshire delegate to the Second Continental Congress. He would serve alongside Josiah Bartlett and William Whipple.
Thornton, like many of the Declaration of Independence Signers, would serve in multiple government vocations before and after the Second Continental Congress. He would serve as a the first president of the New Hampshire House of Representatives, Associate Justice of the Superior Court of New Hampshire and elected to Continental Congress just in time to sign the Declaration of Independence. He would also become a Londonderry Town Selectman, a representative and President of the Provincial Assembly, member of the committee of safety and helped draft New Hampshire’s form of government after it declared Independence from Britain. The New Hampshire Constitution would become the first constitution after the hostilities to England began.
During the war he would become a political essayist and retire from the medical field in 1780 and moved to Merrimack, New Hampshire. Here he would run a ferry with his family until his death in 1803.
Matthew Thornton was known for his hard work ethic, multiple abilities and his honesty. He was known as a man of character which one sees when they look on his gravestone that reads, “An Honest Man.” He was a devoted Christian and a devoted father.