What are the three most important social changes that occurred due to the American Revolution?

The three most important social changes due to the American Revolution were the migration of Loyalists, more political equality, and religious freedom.
The Loyalists made up about one-third of the population of the rebellious colonies. Their devotion to England put them in a precarious position. Thousands fought for the British. Others fled to the safety of the British lines. Their property was confiscated by the colonies. Thousands left America, and most of them ended up in Canada. Their exodus had both social and economic impacts.
The war made the new country more democratic. Those men who fought together against the British expected equality in the new nation. After 1776, property qualifications required for voting were relaxed. One key reason for the war was the colonists' dislike of taxation without representation, and that sentiment carried over into the postwar era. In addition, more commoners began serving in state legislatures.
A third change ushered in by the war was increased religious freedom. The nascent country moved toward separation of church and state. The state of Virginia and Thomas Jefferson championed this cause. In 1786, the Virginia legislature passed Jefferson's Statute for Religious Freedom. Also, the First Amendment to the US Constitution guaranteed freedom of religion.