Oil refineries release billions of pounds of pollution into waterways each year, according to regulatory data. NPR found that pollution is concentrated near places where people of color live.

Oil refineries have lost capacity over recent years, making it nearly impossible to increase supply and stabilize gas prices at the pump.

The drop doesn't signal a rapid descent to the low prices of 2021, but drivers could see modest decreases continue in the coming weeks, analysts say.

The facilities are located in every state, and are threatened by floods, hurricanes and wildfires that can cause dangerous leaks and explosions, according to a federal watchdog.

Coast Guard teams have been dispatched to help determine the extent of the damage from the spill, which is situated roughly two miles off the Louisiana coast. Officials say the source remains unclear.