The border patrol has also found catapults, staircases and loading ramps near the border.
Since 2014, more than 80 individuals have been arrested in the hills for spying on law-enforcement agents working at the border.
Its inhospitableness makes it attractive to the drug traffickers, says the border patrol.
Sandra lives less than 10 minutes from Arizona but she cannot cross over to the US side because she does not have a visa.
A few meters down the road, a kindergarten decorated in bright colors stands in sharp contrast to the wall.
Fuente original: Mexico-US border crossing: By tunnel or by mule: how drugs are moved from Mexico into Arizona | In English | EL PAÍS
