When it comes to petroleum, Mexico was once in a rarefied club of oil-producing states. As recently as 2005, Mexico produced 3.8 million barrels a day, making it the fifth-largest producer in the world, behind only Saudi Arabia, Russia, the United States, and Iran.
But Mexico's primary oil producer, Pemex, hasn't been able to keep pace, in part due to heavy taxation and a lack of funds to find new oilfields and upgrade its infrastructure. By 2016, production had dropped by half and the country no longer even made the top 10 list of producers.