Twelve states were represented by the delegates who signed the U.S. Constitution.
The Constitutional Convention met in Philadelphia in 1787 to revise the Articles of Confederation, but it produced an entirely new framework of government. Delegates from twelve states participated in the convention and endorsed the finished document on September 17.
Rhode Island was the exception. It declined to send delegates, largely because its political leaders opposed a stronger central government and feared the convention might threaten state authority. Rhode Island later became the thirteenth state to ratify the Constitution, doing so on May 29, 1790.
This figure is easy to confuse with both 13 and 39. Thirteen was the number of states in the Confederation, while 39 was the number of individuals who signed. The signing represented twelve states because Rhode Island was absent from the convention.