[Chester B. Stone, Jr.]

As posted above, I live in Mexico. You should not plan on using US$. The tolls will only take pesos, and anytime you use US$, they will clobber you with the exchange rate. What is best is to us a US debit card at Mexican bank ATMs. Be careful which bank card you use since some US banks charge a foreign exchange fee up to 3%. My Schwab debit card has treated me very well over the years. Another point, for many reasons, do not travel at night, and this has nothing to do with safety.