Border tunnels are a critical tool for dealers trying to smuggle drugs between the US and Mexico, but there is a new way to detect them and search for illegal substances.
Historically, US border agents have had to deal with the knowledge that a good amount of trafficking takes place with the help of border tunnels, which are cleverly concealed and built to avoid detection.
With nearly 170 border tunnels discovered since 1990, US authorities have had to become creative in how they fight this situation, which can be dangerous for agents on the ground.
One of the most effective tools available to fight what is one of the biggest problems that plagues the US-Mexico border, is a robot.
The wireless machine, which is also equipped with a camera, can do the job in half the time and with much less risk than sending a human to dig for drugs.
Border tunnels range from very simple -- in which only one person can crawl into the space -- to complex construction complete with ventilation and lighting.
The longest tunnel discovered to date was about a quarter-mile long, but there are small ones which literally only cross from one side to the other.
Some of the tunnels go from Mexico into warehouses or private houses owned by drug cartels, which hire miners and other laborers to dig the earth with simple tools available at home improvement stores.
For the more sophisticated border tunnels -- such as those found in San Diego -- drug dealers will hire engineers and miners to build them. US border authorities estimate the cost of some of these can reach $2 million to $3 million.
The smugglers count on tunnels to, not only traffic with drugs, but arms, and people who want to enter the US illegally.
Those wanting to come to the US pay a hefty price to do it this way and many have died in the process of crossing the border.
Marijuana, which is bulky and difficult to transport, is the most common drug moved through border tunnels.
In November of 2011 authorities discovered a 600-yard tunnel and seized 32 tons of marijuana on both sides of the border. Of that amount, 26 tons were found in the US. This was one of the biggest marijuana sting operations in US history.
Border tunnels are not easy to detect. Many times alert border patrol agents on either side, discover ground that has recently been disturbed or informants will supply information.
According to US Customs and Border Protection and US Immigration and Customs Enforcement, robots have been used for years in the fight against drug and human smuggling.
A robot can explore pipes, drainage systems, and tunnels with ease, while a border agent watches the images from a location outside the tunnel.
Several new robots that can travel through the laberynths that sometimes are built by drug dealers will be added to the existing fleet in Arizona and California.
Some of the newest robots weigh as little as 12 pounds and can get into border tunnels that are only a few feet wide, where a person can barely squeeze through.