The First Independent Colony

New Hampshire was the first of the original thirteen colonies to establish an independent government separate from British authority, doing so on January 5, 1776, more than six months before the Declaration of Independence was signed. The colony's colonial governor had fled to a British warship the previous year, leaving a power vacuum that the provincial congress filled by establishing its own government. The document they adopted is considered the first written constitution for a self-governing body in American history.

Source: Wikipedia