Question

3. What established the process for which states could be admitted in to the Union?

Answer 1

"New States may be admitted by the Congress into this Union; but no new State shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or Parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress."

"The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States; and nothing in this Constitution shall be so construed as to Prejudice any Claims of the United States, or of any particular State."

A new state can't be created without the territory's consent, which is why Puerto Rico held a vote on the referendum. If the territory votes in favor of statehood, the next step is to petition Congress for admission into the Union. Typically, a territory sends representatives and two senators to push for statehood.