The US has tremendous reserves of oil and gas. The most in the world (when recoverable "unconventional" resources are included) but there is not the current economic need, and especially not the political will, to exploit them. Especially not now in 2019.
But back when things were different, there was actually the hope among many that the US would be able to create its own sovereign wealth fund from the oil and gas contained in Colorado's Piceance Basin. The Piceance is currently estimated by the USGS to contain 2 trillion barrels of oil and about 100 trillion cubic feet of natural gas (in all formations), with most of that on Government owned land as there are few private landowners in the Piceance. The US government has been actively trying to unlock that resource for over 120 years. As part of Project Plowshare, they even exploded a nuclear device to fracture the rock enough to allow the oil and gas to flow to the surface naturally. It worked, but the resulting production was far too radioactive to use.
During the oil crisis of the early 1970's, the price of oil rose so high that the Piceance kerogen shale rock became economic to extract oil using the existing technology. The Colony Shale Oil Plant was constructed beginning in the mid-1960's as a pilot project but suddenly went "live" during the Arab Oil Embargo. The US thought this was the key to vast riches and energy independence for the country for centuries to come. Alas, it was not to be. The costs to produce oil were much higher than planned, and the environmental damage from actually having to mine, crush and heat the rock didn't help. They only produced about 270,000 barrels before shutting it down in the early 1980's.
Today the technology to produce oil and gas from the Piceance kerogen at economic prices exists, thanks to the US government funding the required studies. It can be done in situ with little environmental disturbances. But the political will to permit it is gone. And with the cheaper and easier to get Bakkan and Permian Basins currently available, the Piceance is again sort of the sleeping giant of the world's oil fields.