At a Border Patrol station near McAllen, Texas, about 40 people were crammed in a small cell, lying body-to-body on a concrete floor with a stench of body odor hanging in the air. Women and children pressed their faces against the glass windows and doors, peering out at their guards with blank stares.

This is the first stop for people apprehended at the US-Mexico border near McAllen, the place where their fingerprints and photos are taken and a brief interview is conducted by a Border Patrol officer.

Border facilities like this have been overwhelmed in recent months, especially the ones in Texas’ Rio Grande Valley, an area in the southeast corner of Texas about 350 miles southwest of Houston. The valley is the shortest crossing point for the journey north from Central America and the by far the busiest spot.

Overall, more than 55,000 "family units" and 57,000 unaccompanied children have been caught at the border in the past 10 months. The number of children — largely from El Salvador, Honduras, and Guatemala — has more than doubled from the previous year; the number of families crossing has increased by nearly 500 percent.

US Customs and Border Protection granted me a tour of their detention facilities in McAllen after weeks of trying to set up an interview. Many reporters I’ve spoken with have complained about lack of access, and few have been given tours. Border Patrol spokesman Omar Zamora said there was no attempt to dodge the media. Rather, CBP has been overwhelmed with tour requests in recent weeks by journalists and members of Congress.

I was not allowed to record audio or take photos or video, but I had free access to walk around and take notes. On the day I visited, 444 people were being held at the detention facility. According to Border Patrol officers at the center, the maximum capacity is supposed to be 391.

The facility contained 15 cells in a semicircle that faced inward toward a central area with guards. The cells were perhaps 10 to 15 feet wide and 30 to 40 feet deep — size varied — with toilets in the back behind a concrete half-wall that offered minimal privacy. Some of the cells had only six people, but most were packed. The cells had labels outside that grouped detainees by age: children ages 12 to 14, children over 14, adult men and so on. Many of the cells had mothers and smaller children together.

I saw stacks of diapers and baby formula for the children. Border patrol officials told me they've had to change some diapers, but shrugged it off as part of the job. There were placards offering first aid advice and tips on how to prevent the spread of germs. Some people were wearing masks.

In the center of the room, unarmed agents were processing detainees. Some agents did the processing work via teleconference from El Paso. In short, I saw an agency stretched to the limit.

These processing centers are meant to take people in and quickly get them to the next step in the immigration process — either another government-run detention facility, a for-profit prison, or, for the lucky, release to a family member somewhere in the country with an order to appear in court. Others are deported, while some elect to voluntarily return to their home countries and forego the immigration court proceedings entirely.

Border Patrol officials said that children are given priority. The goal is to get them in and out of the cramped detention center quickly, with waits no longer than 72 hours. The wait for adults can be days. One woman I met in McAllen, a Honduran with three children, said she and her kids were detained for nine days. I could not independently verify the claim, but many people have made similar statements about the length of their detention.

A common complaint is the temperature in the centers. Detention facilities along the border are commonly known as ice boxes, or hieleras in Spanish, and are frequently talked about in the Rio Grande Valley. Many speculate that the chilly temperatures are set by the Border Patrol to prevent the spread of disease. Others say that the US government is sending a message to the detainees, making them uncomfortable to keep them from coming back.

“There’s nobody here intentionally making anybody cold,” said Kevin Oaks, Chief Patrol Agent for the Rio Grande Valley sector. “If you have people that don’t normally live in air conditioned locations and have travelled through hundreds and hundreds of miles of heat to get there — you go into a 72- or 74-degree climate, it may seem cold to them.”

Oaks invited me to take a tour of any of the facilities, which he said are all temperature-controlled and set by rules and regulations. I saw two facilities — I could feel immediately that it was at or near a comfortable room temperature. Still, his agents were insistent on showing me the thermostat: 72 degrees.

I did see some people huddled in Mylar blankets provided by the government. Others were sitting comfortably by their sides. In defense of Oak’s position, human beings do experience temperatures quite differently. Building science experts say we're bound to fail if we try and make everybody feel comfortable in a building.

Oaks said it’s also hard to regulate temperature in cells that are constantly in flux: Body heat from 30 people in a small cell can make it feel warmer, then suddenly cooler when 20 people leave.

In response to the urgent situation on the border, CBP also opened a new detention facility two weeks ago in McAllen that's just for children. I got a tour of the new facility, which is an old warehouse. The children were in large, indoor cages behind chain-linked fences — not ideal, but the children do need to be contained and the facility was well ventilated and clean. The kids had access to mattresses and showers, which were not available in the other detention facility, as well as private toilets. AmericCorps teachers were helping children learn some basic words in English. Other children were playing soccer and basketball.

In short, the two facilities couldn’t have been more different. Border Patrol agents didn’t say this directly, but the message I got was that, with more time and money, they could erect better facilities.

The pressing legislative debate is this: How much funding should be provided to create more humane conditions in detainment centers right now? We'll have to wait a little longer to find out. Unable to reach a consensus on a pricetag, Congress is now on vacation.