What states in the US have oil fields?

There are a number of states within the US that have oil reserves. Oil comes from fossil fuels. Most of the oil on the planet was created during the geologic time known as the Carboniferous. Most of the states with reserves or oil fields are on the East Coast, West Coast, and in some southern states. California, for instance, has oil reserves. California's oil is one of the reasons that Los Angeles became a booming economy. However most oil is located just off shore.