I mean the other 2 countries, Canada and Mexico, how similar are both of them to United States?? Both countries have a similar economy and democracy etc, and I think those two countries share things like supermarkets, stores, etc. I suppose the cultural differences are not a lot, that is very nice.
Arguably, Cuba and the Bahamas (at least) border the US. If we get technical, so do Russia and several island nations in Oceania.
Don’t think that’s being technical. The US and Russia are literally neighbors.
You can even see Russia from your backyard.