There is no one important change resulting from the American Revolution. Roles of minorities (women, blacks) changed, economy changed (no dependence on Britain), social hierarchy changed (Tories leaving), etc. Also, the Articles of Confederation were weak (states were not united because there was emphasis on states' rights and not so much on unity), which caused the creation of the much stronger U.S. Constitution.
If you are interested for a change not solely within the nation, it was important that Great Britain recognized the independence of the colonies.
This will have some of the dates you are looking for:
http://colonial-america.suite101.com/article.cfm/effects_of_the_american_revolution
