Space at certain Border Patrol stations has become so scarce that authorities have resorted to transporting immigrants on aircrafts to other parts of the U.S.-Mexico just to be processed.

As first reported by The Washington Post, the flights are conducted by U.S. Immigration and Customs Enforcement (ICE). The first flight left McAllen, Texas, on Friday for Del Rio, Texas. Daily flights are scheduled over the next few days.

It is not out of the ordinary for ICE to transport immigrants on a plane, as they frequently use flights as a way of transferring individuals from one detention center to another. What is new, however, is the practice of transporting recently-arrived immigrants via aircraft to different parts of the border so that they can go through a preliminary booking procedure.

Officials say this is necessary to accommodate the influx of immigrant families that have arrived at the border in record numbers over the last few months. In April, authorities detained 109,144 migrants along the southern border — the highest total since 2007. More than 60% of those apprehended were families or children.

But it hasn’t always been like this. The Trump administration ended vital programs and policies which helped alleviate the number of immigrants in detention.

Beginning in January 2016, ICE had a formal alternative to detention called the Family Case Management Program (FCMP). FCMP was specifically designed for families seeking protection in the United States and allowed families who passed a credible fear interview to be released into the country.

Families were also provided with a caseworker. The program was wildly successful; according to the Women’s Refugee Commission it resulted in a 99.3% rate of immigrants attending their court hearings and a 99.4% rate of attending appointments.

In addition to being successful, it was also cost-effective. Detaining families is expensive, costing upwards of $320 per day. FCMP meanwhile, costs just $38 per day per family unit. For a family of one parent and two children, 20 days enrolled in the FCMP costs $760, compared to $19,200 in an ICE family detention center.

Despite this, ICE chose to end FCMP because they believed it to be too expensive.

“The rates of compliance for FCMP were consistent with other monitoring options ICE exercises under Alternatives to Detention (ATD), which proved to be a much better use of limited resources,” ICE spokesperson Sarah Rodriguez told NBC News in a statement last summer.

President Donald Trump likely isn’t concerned with cost of detaining immigrants given he has routinely asked the federal government to contribute billions to his border wall and the expansion of detention centers.

He is concerned, however, with ending the process of “catch and release” which played a part in why the administration ended the program in June 2017. In the view of President Trump, “catch and release” programs like FCMP allow the government to detain criminal immigrants, then release them into the country where they avoid their court dates and ICE check-ins. All data points to the contrary, however, demonstrating that the vast majority of immigrants follow the rules when not detained.

Meanwhile, the continued increase in the number of immigrants in detention has allowed for the Trump administration to justify its expansion of privatized detention centers. Over the last few weeks the administration awarded three contracts to private prison companies. The three prisons have a combined capacity of nearly 5,000.