Each one of the current 50 states that make up the US joined the Union at some point or another. No states were ever forced to join, and no states were automatic members.
Hawaii
15th
Missouri joined as a slave state and Maine joined as a free state.
No it joined the Union as the 15th US State.
Missouri joined the Union on 10 August 1821 as the 24th US State.
1889
Hawaii 1959.
None. The US did not exist until 1776.
On 12 December 1787 as the 2nd US State.
Texas was the 28th state to join the US.
It is the state of Wisconsin that joined the statehood in May 1848.
Iowa joined the Union as the 29th US State.