I rarely used local pesos. Merchants and tour operators much preferred U. S. dollars. This was especially true in Argentina, where the official exchange rate is about 8.4 pesos to the dollar, but just about everyone you deal with will happily offer 11 or 12 to the dollar.
Small amounts of local currency are useful for bus fares, etc., but if you are cruising in South America, don’t come loaded with stacks of local currency.
