I'm in the US, but when I opened my account a couple years ago I was in Ecuador.
I changed my address to US though.
Where else can I buy?
Gemini is one of the best sources to buy bitcoin in the US. Coinbase has had a lot of problems lately but I guess you didn't know. There are other places like Coinmamma where you can buy bitcoin with a credit card which works worldwide so USA should be easy too. There is also Cex.io where you can buy with your credit card but you need to have it 3D secure card otherwise it won't work.
Hope this helps.