While Summer and I plan on using public transit and taxi services on our trip, I did not want to limit our ability to rent a car. On a trip to Europe when I was 20, I learned that there was a treaty signed in 1949 by the US and other foreign countries that allows for people to drive in other countries while traveling. This treaty has been signed by more than 150 countries around the world. You can get an IDP (International Drivers Permit) from AAA for $20 per person plus the cost of 2 passport photos per person if you do not provide them. You can not purchase these permits outside of the US if you are using a US Drivers License, so make sure you get them before you leave on a trip. Most countries honor these permits, but some do not. There is another permit, the Inter-American Drivers Permit, that is required only by Brazil and Uruguay. AAA also provides this permit at an additional $20 per person plus the passport photos. We are currently not planning on traveling to Brazil due to Visa cost and complications. It just does not seem worth the extra money for us to get the Inter-American Drivers Permits for Uruguay since we do not plan on spending much time there. For a list of countries that honor the different permits go to the bottom of the IDP Application on the AAA website. Keep in mind that you will also need to have your US Drivers License with you to make the IDP valid.