DILLEY, Texas—In the past 10 months, more than 25,000 immigrant mothers and their children caught illegally crossing into the U.S. at the border with Mexico have spent their first weeks in the country living in a sprawling compound of trailers, tents and playgrounds.

The children go to school most days and their parents meet with lawyers and immigration advocates who volunteer at the U.S. Immigration and Customs Enforcement detention center. Almost everyone will ask for asylum in the U.S., a process that could take several years.

For most, the stay will last no more than 20 days, because of a federal court ruling that bars the government from detaining children with their parents for any longer.

The South Texas Family Residential Center in Dilley and a second family detention center about 95 miles to the east in Karnes have become focal points in President Trump’s continuing efforts to crack down on illegal immigration and quickly deport people caught crossing the border illegally. Both are operated by contractors and overseen by ICE.

The Trump administration wants the families’ stay at the detention centers to end only when an immigration judge decides if they should be deported or allowed to stay and live in the U.S. But so far, neither the judge in California who ordered the 20-day limit nor Congress has acted to change the rules.