This 15 August video from the USA says about itself:
This practice is leading more and more immigrants to risk their lives on dangerous journeys through the desert to enter the country instead, says investigative reporter John Carlos Frey. We speak with the Marshall Project reporter about the Barry Goldwater bombing range in Arizona, a vast swath of land across the border from Nogales, Mexico. The area is part of an incredibly dangerous migrant path, but aid workers are not allowed access to the site. Frey estimates hundreds of immigrants could have died there in recent years but that their bodies have not been recovered.
The brutality of borders. Mass grave revealed at Arizona Air Force bombing range. By Norisa Diaz, 18 August 2018.