Which companies use only American drilled oil?

Several companies emphasize the use of American-drilled oil, including major players like ExxonMobil, Chevron, and ConocoPhillips, which source their crude primarily from U.S. reserves. Additionally, smaller companies like Devon Energy and Pioneer Natural Resources focus on domestic production. However, most large oil companies often have a mix of domestic and international sources, so it's essential to verify their specific sourcing practices.