Total U.S. crude oil production grew 11% in 2019, to 1.24 million barrels per day (b/d), the Energy Information Administration (EIA) reported.

This increase in production was led by relatively light and less dense crude oil and was largely the result of growth in crude production from shales and tight rock formations.

Now shales and compact rock formations are more accessible due to continued advances in horizontal drilling and hydraulic fracturing.

Inputs from U.S. refineries have also become lighter over the years as refineries use less imported, heavier crude, as well as more lighter, domestically produced crude oil to process into by-products of the oil.

Oil with a higher API gravity is lighter or less dense.

Crude production with an API gravity greater than 40 degrees grew from 5.8 million b/d in 2018 to 6.7 million b/d in 2019.

Crude oil 

The United States continues to import crude due to variations in crude quality. America’s refining capacity is configured for a wide range of crude inputs, allowing refineries to run the most economical variety of oil.

Heavier oil tends to be priced lower than lighter crude, providing an incentive for refineries to use heavier crude if they have the capacity to do so.