Yesterday I married Vanessa and Brian who will actually be traveling to Mexico on Saturday for a destination wedding. They will be having a ceremony on the beach but learned it can be quite difficult to make the wedding legal in Mexico. I did a little research to learn what is required to be legally married in Mexico and US. Here is what I found.
You don't need to be resident in Mexico in order to get married there. You'll will need a passport and your tourist permit. You will also need chest X-rays and blood tests. These must be done locally in Mexico, as the results of the blood tests and the X-ray documentation must be in Spanish and the tests need to be done within a certain time frame of the Marriage Application Form being completed. Note, not all Mexican States require the Chest X-rays so check locally or ask your wedding planner.
Ohio does not require you to have witnesses but in Mexico you will need to have 4 witnesses present at the legal ceremony. They must have valid identification: usually a valid Passport is used, but other forms of government-issued identification are valid too.
Your Marriage Certificate will be valid world-wide, BUT you should get your certificate 'legalized' in Mexico to ensure it is legally accepted when you get back home.