Why does the World Cup always take place in different countries, but the Gold Cup is always in the US?

I know it's not always there, but they almost exclusively host it. Mexico could host it more often. Canada could host it. Costa Rica and a whole bunch of other countries. It's not such a big tournament. For some reason it even seems that Mexico plays all of its friendlies in the US. I could not picture England playing all of its friendlies in Scotland.