Needs approval of Canadian citizens. They need to vote it up. Also, people in DC have been wanting statehood forever. There were people who said there was something that required states to enter the union in pairs. So, PR was always the candidate to pair with DC - I haven't found that rule, though.

Article IV, Section 3, Clause 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 first clause of Article IV, Section 3 authorizes Congress to admit new states into the union. It is sometimes called the Admissions Clause, the Admission Clause, or the New States Clause.1

The Admissions Clause contains two main limitations on congressional power to admit new states. The first limitation is based on the constitutional text: when a proposed new state is formed from territory in the jurisdiction of an existing state or states, the consent of the affected state legislatures is required (in addition to congressional approval).2 For example, Virginia’s consent was given to the admission of the state of Kentucky, formed out of Virginia’s western regions in 1792.3

Because the Clause uses a semicolon instead of a comma after the phrase no new State shall be formed or erected within the Jurisdiction of any other State, a literal reading of the text might incorrectly suggest that the Constitution categorically forbids forming a new state out of the territory of an existing state.4 The drafting history of the Admissions Clause shows, however, that the Framers contemplated that new states could be formed from the territory of an existing state, if that state consented.5 In practice, Congress—beginning with the First Congress6—has several times admitted new states formed out of the territory of a consenting existing state without constitutional controversy.7

The second limitation, known as the equal footing doctrine8 is rooted in long-standing congressional practice9 and judicial interpretations of the Admissions Clause. Under the equal footing doctrine, new states must be admitted on equal terms with all of the powers of sovereignty and jurisdiction which pertain to the original states.10 In particular, Congress may not impose conditions on a state’s admission that would diminish the equal sovereignty of the states.11

Thirty-seven states have been admitted to the United States under the Admissions Clause. Vermont was the first in 1791,12 and Hawaii the most recent in 1959.13 Beyond requiring at least one act of Congress for admission (and, if applicable, the consent of affected state legislatures), the Admissions Clause leaves the details of the admission process to congressional determination. Most states were first organized by Congress as federal territories before their admission as states,14 but that is not constitutionally required. Texas, for example, was an independent republic before it was annexed by the United States and admitted as state in 1845.15

https://constitution.congress.gov/browse/essay/artIV-S3-C1-1/ALDE_00013708/