I believe there are some banks that have remittance agreement with some of the banks in Mexico that you can use as a conduit to transfer money from your US checking account to your banking account at a bank in Mexico.
I am not sure how many banks has this, but if you follow the link below, this one is from Wells Fargo Bank.
Here is a link to Wells Fargo Bank
https://wellsfargo.com/per/intl_remittance/mexico
From the discription, they work with BBVA Bancomer, Banorte, HSBC, or Telecomm Telegrafos
