Lynch also served as a delegate to the Commons House of Assembly from Prince George and was a member of the 1765 Stamp Act Congress before eventually being elected to serve in Philadelphia on Congress in 1774.
In 1775, Lynch was appointed with Benjamin Franklin and Col. Benjamin Harrison as advisors to General George Washington. He would soon fall ill being rippled by paralysis, so his son, Thomas Lynch Jr., was selected by the South Carolina Second Provincial Congress to join him in Philadelphia. The two made history as the only father and son team to serve the Continental Congress. The younger Lynch would make history again as the 52nd signer of the Declaration of Independence.
The plantation was sustained by rice fields and served as the family's primary source of income until the Civil War.