President-elect Donald Trump has been making waves even before taking office – apparently he wants to be like Putin and take over some neighbouring countries, whether they want it or not. But has he really thought this through?

If we assume that the US constitution will stay substantially the same, adding Canada as the 51st state would increase the population of the United States (currently 346 million people) by 40 million Canadians. Presumably these new US citizens, like most others, will be represented in the US congress. The history and practice of “apportionment” – figuring out how many seats each member state of the US gets in the House of Representatives – is somewhat complicated, but the number of representatives is currently defined to be 435, and the distribution to states goes according to census results, based on the Huntington-Hill method. I haven't actually run the math, but given that Canada has roughly the same number of inhabitants as California, it stands to reason that their delegations to the House of Representatives should be about the same size. Right now, California sends 52 representatives to the House. If the number of members remains 435, every state can expect to have the size of their delegation cut by approximately 10% to make room for Canada, so there would be 46 (or so) representatives from the Golden State and about the same number of new representatives from Canada. Since few of those are likely to be MAGA-style Republicans and the Republican party currently has a majority of only 5 seats in the House, that is not exactly great news for the GOP.

The number of votes each state has in the Electoral College, which elects the President of the United States, is equal to the size of its congressional delegation. With 48 electors (46 + 2 because the state of Canada will be entitled to two senators) and what can reasonably be assumed to be a dependably centre-to-left-leaning majority, this will render the idea of itsy-bitsy little election-deciding “swing states” like Pennsylvania or Ohio obsolete and ensure that no Republican will be elected President for the foreseeable future. (This can be all the same to Trump, who after two terms as POTUS isn't eligible for re-election anyway, but as a matter of principle it kinda sucks if you're a wannabe GOP president.)

So this takes care of the Electoral College and the House. What about the Senate? It would be strange if Canada as a whole became the 51st state – after all, it's larger on its own than the other 50 US states combined –, so if we stipulate for simplicity that each of Canada's existing ten provinces and three territories became its own US member state, then because every US state is entitled to two senators, Canada would add 26 new members to the Senate. The Republicans currently (as of the 2024 election) have a 6-seat majority in the Senate, so it is safe to assume that the Senate, too, will be firmly in Democrat hands once Canada joins the Union.

Of course the assumption at the beginning was “If the US constitution stays substantially the same …”. Could Trump change the constitution in some way that would mitigate the “Canada effect”? Perhaps, but probably not. The US constitution is remarkably difficult to change – in the 236 years since the constitution was enacted, only 27 proposed constitutional amendments out of hundreds actually became official. For starters, an amendment must command a two-thirds majority in both the Senate and the House (hard to get right now, for a partisan thing) before it can be sent to the states for ratification, and three quarters of the states must then ratify it, theoretically – according to convention – within seven years. That would be 38 states, but currently the GOP has a majority in the legislatures of fewer than 30 states – so it would be highly unlikely that a constitutional amendment that gave a big advantage to Republicans could be pushed through in the prescribed way. That of course leaves the possibility of some sort of coup d'état; Trump could simply declare himself king of America and rescind the constitution as a whole, but whether the resulting chaos and turmoil would leave room for little ancillary questions like whether Canada should be a US member state is anyone's guess.

We can wait and see whether Trump will eventually figure out that adding Canada to the USA as one or thirteen new states or anything in between would effectively be political suicide for his party. Perhaps he will instead redouble his efforts to add Greenland, which could just become a “territory” like Puerto Rico or Guam (they're all islands, aren't they?) and wouldn't require big changes to Congress, or to reconquer the Panama canal zone? Mexico is probably not that interesting because after all it is full of Mexicans, whom Trump is working very hard to keep outside the US. Interesting times.