The main purpose of the Mayflower Compact, signed in 1620 by the Pilgrims, was to establish a form of self-governance in the New World. This document created a framework for political organization and community cooperation among the settlers, emphasizing the importance of consent and majority rule. It laid the groundwork for future democratic governance by asserting that the colonists would govern themselves and create laws for the good of their new society, paving the way for the development of constitutional democracy in America.