You know, VICE News has done several stories on this subject. One of the more interesting ones was that they are stopping them at the border, but only allowing 60 or so people per day to get processed for asylum. And, they have to wait in Mexico to be processed.
One guy who had been caught crossing illegally said that the only reason he did it was because his son was sick, and he knew that if he crossed illegally he would get medical help for his child QUICKER than if he waited for his number to come up for asylum. He crossed illegally because he wanted to save his child.
Another woman who was interviewed said that she waited for her number to come up (trying to do it legally), then when she was interviewed, they told her that her number wasn't any good any more, and she had to go back to the end of the line and start over. She said it was because of that experience she was considering crossing illegally with her kid.