[2][3] While a member of the 1776 Fifth Virginia Convention he chaired the committee which passed what became the Lee Resolution, the call for the Second Continental Congress to declare independence from Great Britain.

[5] Upon his father's death in 1749 or 1750, Cary inherited over 4,000 acres, lying on both sides of the Willis River, in what would eventually become Cumberland and Buckingham counties.

[8][9] In 1764, he served on the committee of Burgesses that wrote resolutions against the proposed Stamp Act, but the following year he voted against Patrick Henry's Virginia Resolves as being premature and too inflammatory.

[1] As tensions with the mother country escalated, in 1773 Cary served as a member of Virginia's committee of correspondence.

He operated Chesterfield Forge, which fabricated iron, starting in 1750, and ending in 1781, when it was burned by Benedict Arnold.