Congress asked the 13 original colonies to form governments for themselves, so the colonies began writing and adopting new constitutions to become sovereign and independent states. . However, the national government was weak and states functioned like independent countries. So, at the 1787 Constitutional Convention, delegates from the different states decided to a plan a stronger federal government with three branches (executive, legislative and judicial) all of equal power. As a result, the US Constitution was signed on September 17, 1787 in Philadelphia.