After hitting a 17-year low in April, border agents have seen apprehensions climb from 11,125 to nearly 22,300 people in August, as people rushed to enter before Trump builds a long-promised security wall and enacts tougher border-security measures.
They are only speculating that a wall is the reason. Personally, I think a lot of it has to do with Trump's recent support of a DACA (DREAMER) amnesty and talk of a future attempt at comprehensive immigration reform.