The Mexican government is helping and aiding them. Right out in the open.
Not only is illegal invasion prosperous to Mexico (gets rid of their undesirables and also Billions in ca$h flows from US back to Mexican economy), the Mexicans learned from Erodgen in Turkey.
Erdogan threatens to let 3m refugees into Europe
Erdogan has successfully employed the "refugee" card for several years now, and does so to this day. If he doesn't get his way on something, he floods the EU with even more "refugees."
Our "friends" in Mexico are using the "refugees" as a bargaining chip for NAFTA renegotiation's with Trump.