American citizens must have a tourist visa, which can be purchased before arriving or at ports of entry. Requirements are fairly complex, so the latter is not recommended. At the time of this writing, Americans entering Bolivia must pay $135 USD for a tourist visa and are required to receive the yellow fever vaccine. If you want to stay longer than your 30 days, you have the option of overstaying your visa and being fined (Bs)20 for each extra day you stay, purchasing a 30-day extension for (Bs)150, or hopping across the border into Peru and back with a new visa. Canadians pay a fee of 30 USD, and citizens of Australia, Switzerland, the United Kingdom, and New Zealand need only a valid passport, and receive a free 30-day visa upon arrival in Bolivia (it doesn’t hurt to ask if they will extend it to 90).