Single adults racing across one part of the U.S.-Mexico border are dressing as drug smugglers to make it less likely they'll be caught.

Approximately 90% of unauthorized immigrant adults arrested by federal agents based in Tucson, Ariz., are dressed in head-to-toe camouflage and wear carpet booties that are also covered in a camouflage pattern.

Historically, individuals who were arrested near the border and dressed in camouflage and carpet booties were drug smugglers. Agents refer to these types of drug smugglers as “mules” because they carried 40- to 50-pound backpacks of marijuana and ArmaLite Rifles through the desert.

The single adults may have criminal histories, have been deported, or be trying to evade detection for other reasons. The smugglers running them are investing in the outfits to help this demographic sneak across.

Illegal immigrants wearing camouflage and carpet on the bottom of their shoes in hopes of avoiding detection. (Customs and Border Protection)

Since the start of the fiscal year in October, more than 31,000 single adults have been apprehended in the Tuscon area after illegally crossing.

"Of that 31,000, I would estimate more than 90% to be in camo," Pete Bidegain III, a regional spokesman for the Border Patrol, wrote in an email to the Washington Examiner.

Before crossing from Mexico’s northern state of Sonora, smugglers make each person who has paid thousands to get into the U.S. put on a sweatpants-type material camouflage outfit over the clothes they are already wearing.

“The smugglers on the south side of the border in our sector essentially require it,” Bidegain said during a phone call.

The camouflage outfits allow people to blend in with the desert landscape while the carpet booties prevent them from leaving behind tracks that would otherwise lead agents right to them. Only single adults, not families and children, are being apprehended in the camo outfits. Bidegain explained that families do not need to blend in with the terrain because they are seeking out law enforcement to claim asylum and not trying to avoid U.S. officials.

The Tucson region began seeing this new trend of unauthorized immigrants wearing camo five years ago. Now tens of thousands are in on the act.

How many Border Patrol agents do you see in this photo? The majority of apprehensions in #TucsonSector are illegal aliens dressed in full camouflage with carpet booties over their shoes trying to evade arrest. @CBP pic.twitter.com/ycZ1xRUlTv — CBP Arizona (@CBPArizona) June 19, 2019

“That really just speaks to the control issue. On our stretch of border here in Arizona, everything is 100% cartel-controlled. So family units are directed to cross in certain places, told to walk across at certain times,” said Bidegain. “A lot of times, it’s connected to other activity — the family units will be close, knowing that it’s going to tie up some of the Border Patrol resources.”

Agents typically encounter a group with three to 15 people. Sometimes the family groups are released at the border to draw Border Patrol resources while nearby, a camouflaged group is told to rush across, he said.

The Tucson region runs up against 262 miles of the international border.