In 1796 - Tennessee (first state, resulting in a new territory).
In 1817 - the Mississippi.
In 1820 - Maine
In 1845 - Florida (reclaimed at the time of the Spaniards).
In 1863 - West Virginia (freedom-western outskirts of Virginia).
In 1790 formed the District of Columbia (geographically coinciding with the city of Washington). This county once planned as the site of the US government meeting.