Hard to find exactly how much US foreign aid is sent to Mexico - I did find this. It’s almost a $billion annually. That should stop and we use those tax payer funds for the wall!!
http://listosaur.com/politics/top-10-recipients-of-united-states-foreign-aid/
There are also zillions of projects in Mexico that get U.S. taxpayer money to help (finance) with. City, county, state, and federal money and most of the time the taxpayer has no idea.