Twelve states were represented at the 1787 Constitutional Convention in Philadelphia.
The convention met from May 25 through September 17, 1787, at the Pennsylvania State House, now called Independence Hall. Delegates came from 12 of the 13 American states. Rhode Island declined to send delegates because it opposed efforts to strengthen the national government.
The gathering was initially authorized to revise the Articles of Confederation. As debate progressed, however, many delegates concluded that the existing system could not be repaired through minor amendments. They instead developed a new Constitution with separate legislative, executive, and judicial branches.
Fifty-five delegates attended at least part of the convention, although attendance changed over time. Thirty-nine ultimately signed the Constitution. The convention’s work then moved to the states, where ratifying conventions decided whether the proposed government would take effect.