Coinbase is one of the best bitcoin exchange platform in United states and other countries. Major business came from USA because they have very simple procedure to operate and send btc in a moment with the authentication. You can buy btc from credit/debit card, you have wire option here and bank connection. According to crypto currency customer they are liable to buy btc in usd and convert it into some other crypto currency like bitcoin and etherium. If you have any issue with the coinbase while purchasing anything you can contact with coinbase customer service
https://www.coinbasephonenumber.com