Final answer:
The worst oil-caused environmental disaster in North America occurred during the Deepwater Horizon oil spill in the Gulf of Mexico in 2010.
Step-by-step explanation:
The worst oil-caused environmental disaster in North America occurred during the Deepwater Horizon oil spill, which started on April 20, 2010 in the Gulf of Mexico near Mississippi. The blowout resulted in an estimated 4.9 million barrels (210 million gallons) of oil flowing from the ruptured well beneath the water's surface. This spill was the largest marine oil spill in the history of the petroleum industry.