As I stated above, damn it's been a year since I last posted. The great thing is you can go back and watch the Declaration is Read post from last July 4th.
A problem with many Americans is they believe that the Declaration is a government-creation document, when all it is is a set of grievances against King George III and the British government that told them why we were declaring ourselves independent of them. It was the Articles of Confederation that was our first "Constitution" and that really wasn't ratified until early 1781.
The Articles had many problems as there was no central Judicial Branch to resolve problems between states, no central Executive Branch to enforce the law, no taxing ability, no common currency, etc.... This made the central government weak basically created 13 states, whose power was supreme over the central government. This lead to the economic problem of trade between the states and rebellion, like Shay's Rebellion in Massachusetts.
The U.S. Constitution was created to to end these problems with a federal government that was supreme.