SAN DIEGO (AP) — A new policy to deny asylum to anyone who shows up on the Mexican border after traveling through another country threatens to exacerbate overcrowding at severely strained U.S. immigration detention centers and makeshift holding areas.

Photos and video of Vice President Mike Pence’s visit Friday to McAllen, Texas, showing men crammed behind chain-link fences offered the latest glimpse into squalid conditions at Customs and Border Protection facilities. Women are being held in smaller tents at the station.

The Border Patrol housed 900 people in an area with capacity for 125 in El Paso, Texas, according to a Department of Homeland Security’s internal watchdog report on an unannounced visit in May. Inspectors saw detainees standing on toilets to gain breathing space. Agents described detainees being held in standing-room-only cells for weeks.

A sharp drop in illegal border crossings, coming during a seasonal decline as summer heat sets in, has eased pressure temporarily. The Border Patrol has fewer than 10,000 people in custody, down from 19,000 in May, according to a U.S. official who was not authorized to share the figures publicly and spoke on condition of anonymity.

The Border Patrol’s Rio Grande Valley sector, the busiest corridor for illegal crossings, was the only one of nine sectors on the Mexican border over capacity on Wednesday, with about 6,000 detainees, the official said. El Paso has plummeted to 500 detainees.

Still, the space crunch is daunting and holding people who are denied asylum until they are deported can only pose more challenges.

Immigration and Customs Enforcement operates long-term detention centers that are far better equipped, but that agency is also heavily burdened. It is holding more than 53,000 people, hovering near an all-time high and above its budgeted capacity of 45,274, including 2,500 spots for families.