A report released by the Government Accountability Office (GAO) this week demonstrates all tunnels discovered were under the U.S.-Mexico Border.

The report revealed that from fiscal years 2011 through 2016, 67 cross-border smuggling tunnels were discovered along the U.S.-Mexico border. Sixty-two out of the 67 smuggling tunnels were in the Border Patrol’s Tucson, Arizona, and San Diego, California, sectors which are known strongholds of the Sinaloa Cartel.

The GAO also found there were 534 detected ultralight aircraft incursions and 309 detected incidents of drug smuggling that involved small fishing vessels. Seventy-five percent of the maritime drug smuggling incidents occurred on the Pacific coast.

“While these methods account for a small proportion of known smuggling, they can be used to transport significant quantities of drugs or for terrorist activity,” the report noted.

Breitbart Texas has reported extensively on the different techniques used by Mexican cartels to smuggle narcotics and humans into the United States. Most recently, Tucson Sector Border Patrol agents discovered two tunnels within the span of a week. The first was on April 26, when agents discovered a tunnel that extended into the United States by 60 yards and had collapsed. The next tunnel was reported by Customs and Border Protection (CBP) on April 28, where agents found one under construction.

In April 2016, U.S. authorities found what they believed was the largest ever cross-border smuggling tunnel along the California-Mexico Border. The tunnel was estimated to be over 800 yards long and included an elevator, lights, rails, and a ventilation system.

Ryan Saavedra is a contributor for Breitbart Texas and can be found on Twitter at @RealSaavedra.