Where to buy pesos

Thanks briansue. The cajero automticas reference is the perfect source to find ATMs. It can be used all over Mexico. We generally stay over night at the truck stop in Eagle Pass and then in the morning go down Main St. to S Monroe St. and follow it around to the bridge into Mexico. There are banks just off of Mirador St.in Piedras Negras that we didn't know about. Thanks, it will be easy to get pesos from the cajero automaticas there.