1990年，执法人员在亚利桑那州道格拉斯发现了第一条非法跨境隧道。从那时起，美国边境巡逻队和毒品执法局至少发现了至少106个地下途径，越过墨西哥与亚利桑那州，亚利桑那州和亚利桑那州和州之间的边界加利福尼亚。美国边境巡逻队说，这些隧道是基本的，旨在实现使用它们来走私毒品和人的毒品卡特尔和人口贩子的目标。

As cross-border traffic becomes more lucrative, so does the engineering and construction of the tunnels. The U.S. Border Patrol plugs discovered tunnels quickly, but new routes appear seemingly overnight.

圣地亚哥边境站的美国监督边境巡逻队兰斯·莱诺尔（Lance Lenoir）表示，非法跨境隧道根据三个层次进行分类：基本，互连和精致。基本的隧道是“地鼠洞”，因为它在围栏下距离短距离。互连的隧道在市政基础设施（例如下水道系统和雨水流水线）中点击或挖出。复杂的隧道是由通风和电气系统建造的，具有某种类型的运输机制，用于移动麻醉品。

Lenoir says the tunnel used by Joaquin “El Chapo” Guzman, head of the Sinaloa Cartel, to break out of Altiplano Federal Penitentiary last July in Juarez, Mexico, was a sophisticated passageway that used a motorcycle adapted to run on rails from mines.

经纪人完成调查并清理隧道后，执行了四部分的修复过程。

Lenoir说：“一个隧道入口团队进入并有效地绘制了隧道，以获取我们所寻找的位置以及我们必须钻探的位置。”

Agents then use sonde transmitters to pinpoint the tunnel’s path on the surface.

“代理通常在隧道中携带发射器，然后您将一个定位器上方带到该发射器上的零，这给我们带来了X的地面。[X]在准确的程度上告诉我们我们可以在那里钻探。”他说。

最终，边境巡逻人员用混凝土将隧道封闭，尽管其中一些最基本的人仅被土壤填充。

“We get an auger bit and drill until we intercept, and then the concrete trucks come in,” Lenoir says. “It is usually a slurry mix, but for the immediate border area, which is usually within 90 to 120 feet, I usually fill that up with 3,000-psi concrete. Wet slurry cement is pretty easy to pick through … but with the 3,000 psi, they aren’t going to pick through that.”

代理还将舱壁放置在边框上，并检查系统。这种密封方法非常昂贵，国会已专门用于用于此目的的资金。

For the most part, the Mexican government performs little to no remediation, Lenoir says.

George Trevino, Tucson-sector Border Patrol agent, says the tunnels are more expensive than traditional smuggling methods but are constructed quickly. Some tunnels are used multiple times, but others might be used only once. “If they used it for two weeks and, in those two weeks, they were able to pass over $10 million worth of narcotics, that would probably outweigh the cost of building the tunnel, so it is worth it for them,” he says.

市政基础设施也起着关键作用。Nogales坐落在数英里的管道，导管和排水系统上，这是走私者的完美预制结构。

负责Nogales边境巡逻站的副巡逻队兼政府跨境隧道专家Kevin Hecht表示，他们可以在任何现有的基础设施中开始。他说：“隧道可以从墨西哥的现有排水系统开始，并在排水系统之间和美国隧道之间进行挖掘。”

他说，运气在发现隧道方面起着重要作用，密封它们是公共安全和健康的问题。

赫希特说：“这些非法跨境隧道中的每一个都是死亡陷阱。”“他们每个人都没有误会。”