There are a few financial institutions in central Bs. As. that exchange social security checks but they have to have the treasury of state emboss on it. They work as cuevas. There are few. Some used to exchange regular American checks but as of September of 2013 they stopped, just SS checks for now. If you have an American account and a debit card you can just travel to Colonia Uruguay where you can get American Dollars out of any ATM. You can travel by Buquebus or Sea Cat. Sea Cat is cheaper and you almost always get to go on a Buequebus. The trip on boat is one hour and costs just about 600 pesos, maybe a little more. At the Blue Dollar exchange rate it's less than 50 bucks. Don't don't tell them your American or try and pay with an American credit or debit card because you will get charged American rates, which I think is about 340 American Dollars (insane). Go to one of the offices and pay cash, unless you have an Argentina debit or credit card. I but my tickets over the phone with an Argentine Credit Card. Plus, you get to buy American goodies at the the Freeshop, yay! I always but Reese's peanut butter cups and Jolly Ranchers when I go. Hope the info helps.