Context: Donald Trump spewing bullshit about annexing Canada and Greenland. Meanwhile, Congress has been dragging their feet for YEARS on resolving Puerto Rico's territorial status.
Citizens living in US territories do not receive equal representation in congress. For instance, PR has one "delegate" to the House (not an official voting member) and no senators. Taxation without representation.
Although, at this point I wouldn't blame PR if they changed their minds about wanting to become the 51st state.
Pretty sure by 51st state he means Puerta Rico like status. If the entirety of Canada was considered 1 state it may as well be.
There's no way he'd annex Canada then give them the right to vote. It would be 2 more Democratic Senators, a massive leftward shift in the House, and would have more electoral college votes than any other state - all going to the Dems.