After the Parliament of Great Britain introduced a direct tax on the colonies of British America requiring many printed materials to include a revenue stamp, delegates from most of the colonies gathered in New York City in 1765 for the Stamp Act Congress.
The Stamp Act Congress is considered the first ever meeting of elected representatives from several American colonies. The Congress made numerous declarations which, while still proclaiming loyalty to the crown, announced the unconstitutionality of the Stamp Act.
This video discusses the background to the Stamp Act Congress in more depth and explains the response from the colonies and the British. The events surrounding the Congress became known as the American Revolution, not to be confused with the American War of Independence.