US production of oil and related liquids such as ethane and propane was neck-and-neck with Saudi Arabia in June and again in August at about 11.5m barrels a day, according to the International Energy Agency, the watchdog backed by rich countries.
With US production continuing to boom, its output is set to exceed Saudi Arabia's this month or next for the first time since 1991.
Riyadh has stressed that the rise of the US should not detract from its own critical role in oil markets. It says it has the ability to increase its output by 2.5m b/d if needed to balance supply and demand.
Prince Abdulaziz Bin Salman Bin Abdulaziz, Saudi Arabia's deputy oil minister, said earlier this month that the kingdom was the "only country with usable spare oil production capacity".