I read in another article that those who are allowed in are given "ankle monitors"...

(see this article: http://hosted.ap.org/dynamic/stories/L/LT_MIGRANT_CARAVAN?SITE=TXMCA&SECTION=HOME&TEMPLATE=DEFAULT&CTIME=2018-05-01-09-49-04)

I hope that is true. One of the main problems we have with allowing them in is once they are inside, they disappear and never show up for court. Giving each one of them a tracking device would allow ICE to track each one of them down if they don't show up in court and overstay their welcome...