The US gov. loves fees (they're not taxes, so they're okay, right?)

Here's what the Feds charge you (minimum) to leave the country and come back.

US International Departure Tax $14.10
US International Arrival Tax $14.10
US Immigration Fee $7.00
USDA APHIS Fee $4.95
US September 11th Security Fee $2.50
US Passenger Facility Charge $3.00

The last two increase if you have connecting flights in the US.

RANT: Why on earth must you pay an immigration fee and departure & arrival tax ($35.20 total, plus $4.95 USDA fee) at the airport but not when driving across the border? Oh, right, because people would realize how blatantly unfair it is to charge people to come back to their home country if they had to pay cash on the spot instead of a hidden fee.

The Mexicans seem to charge the following (at least into MEX):

Mexican Tourist Tax $19.39
Mexican Airport Departure Tax $22.28

There you go.