I don't expect the entire population to know where every city is in the world, but if you work at the post office, you should probably know where the major ones are. When I have a package to be mailed to Seoul, the world's 3rd largest city, I kind of expect you to know that city is in Korea. Especially when the US does a lot of international business with Korea and we get stuff from Seoul daily. Also, please don't lecture me that you can't mail packages to North Kroea. Seoul is not Pyongyang.