Admitted on Dec. 7, 1787, Delaware was the first state to join the Union. The 13 original colonies one by one became the first 13 states in the new nation according to the date on which each ratified the Constitution.
The second state, Pennsylvania, followed Delaware five days later, and New Jersey became the third on Dec. 18, 1787. In January 1788, two states were admitted: Georgia and Connecticut. Massachusetts joined in February, while Maryland joined the Union in April and South Carolina in May. New Hampshire, Virginia and New York became states over the summer of 1788, and North Carolina joined in November 1789. Rhode Island became the final of the 13 colonies to be admitted as a state on May 29, 1790.