[pluma]

The "52 states" thing seems to be a common false memory: http://www.debunkingmandelaeffects.com/51-or-52-states-in-th...

Personally I also remember (as a child) thinking that the US had 52 states but that's mostly because "51st state" is a common expression I likely came across frequently enough to think that there are at least 51 states, 50 feeling too rounded and 52 being a close enough number that frequently pops up elsewhere (52 cards in a deck, weeks in a year).

I don't like the term "Mandela effect" because of the pseudo-scientific connotations, though. It's just a false memory and in many cases it's not even a memory, just a misconception (like thinking there are penguins at the North Pole because it's easy to mix up the Arctic and Antarctic or to mistake puffins for some kind of penguin).

EDIT: As for Korea: googling yields several claims of people misremembering its placement on the map but if I had to guess I'd blame news reports that like to highlight countries on the map by showing them in isolation or exaggerating their borders by creating a small gap around them.

[WingH]

Also the fact most US maps show Alaska and Hawaii semi-separately makes me think its 50 plus 2.

[pluma]

Also DC not being a state as well as all the "territories". I'm pretty sure I as a child I thought DC counted as a state.