Mexico

The April 20, 2010 Deepwater Horizon oil rig explosion in the Gulf of Mexico killed 11 workers and released ~4.9M barrels of oil — the largest marine oil spill in history. BP, Transocean, and Halliburton's cost-cutting and safety failures are documented; allegations of regulatory capture and concealment of spill volume are partly supported.

The 1947 crash of a high-altitude Project Mogul balloon near Roswell, New Mexico that was briefly described by the US Army as a recovered "flying disc" before being reclassified as a weather balloon — and later, in 1994, as a classified Soviet nuclear-test surveillance balloon.