What to do?
First, before you leave the U.S., call your bank and tell them you are traveling to Mexico and not to block your credit card! You will give them departure and return dates.
Now, you have in your pocket a handful of dollars, a credit or debit card and you are flying direct from Houston to Oaxaca. If you plan to take a taxi or shuttle van from the Oaxaca airport to your hotel in the city or to Teotitlan del Valle, you will need pesos to pay for the ride. In this case, you will need use a money exchange service at the Houston airport. It will cost you a little more in the exchange rate (fewer pesos) but you will not be inconvenienced. I recommend changing $50 USD this way to get you started until you can get to an ATM.
The Oaxaca airport ATM is on the second floor mezzanine.
There is no ATM in Teotitlan del Valle!
There are plenty of ATM’s in Oaxaca city!
ATM’s give you the best exchange rate. Do not use Traveler’s Checks. They are useless. No one accepts them.
If you use a money changer or bank — to change dollars to pesos — you will need to present your Passport.
If you are connecting in Mexico City, be sure to use one of the many ATMs there in the international airport to get pesos. I only use ATMs and avoid the money exchanges. It cost more to change dollars to pesos from a money exchange than it does to withdraw pesos from an ATM. Leave your dollars in your checking account and use ATMs.
If you are a Bank of America customer, there is no service/transaction fee charged when you withdraw cash from a Santander Bank ATM. B of A owns 50% of them!
Where to Find ATM’s in Oaxaca city? These are clustered on Av. Independencia across from the Zocalo between Macedonio Alcala and Av. Garcia Virgil. There are also banks on Garcia Virgil between Independencia and Morelos. Banks with ATMs can also be found on the Periferico in the major shopping center that houses Fabricas de Francia and Soriana, and on Heros de Chapultepec on MEX 190 as you head out of the historic district toward Teotitlan del Valle.
Mexican banks are Santander, Bansefi, Banamex, Bancomer, HSBC, ScotiaBank, and Banorte. Santander is partly owned by Bank of America. If you are a Bank of America customer there are no service fees to use the ATM.
Rural Mexico is a cash economy. Only larger merchants take credit cards (along with hotels and restaurants) because it costs so much (over five percent) for them to pay the fees. Many shops will offer a 10% discount if you use cash.
If you are traveling to Teotitlan del Valle and staying there, you can either get pesos at an ATM in Oaxaca city before you leave town, in Santa Maria Tule on your way to the village, or at the ATM in Tlacolula the following day, which is 10 minutes away by taxi or car. There is a Bansefi in Teotitlan del Valle, but is is used by locals who stand in long lines to get money wired to them from relatives living and working in the U.S.A. There is not an ATM there.
Concerning personal checks: I always bring a couple of checks. Small rug merchants in Teotitlan del Valle may take a personal check rather than waiting for you to go to an ATM to get cash If they don’t take a credit card (most don’t). Make sure your checks are not creased and that there are no tears or folds on the edges. The money changers are very particular.
Mexperience has a useful description of Mexican banks and how to do banking business in Mexico.