The town that is still burning underground is Centralia Pennsylvania.
Centralia Pennsylvania has been burning underground since the year 1962.
The cause of the burning underground in Centralia Pennsylvania is a fire that started in an abandoned coal mine and it's believed to be the worst coal seam fire in the United States.
The exact cause of the coal mine fire and start date of the fire is unknown.
The fire is burning over 3,700 acres and up to 300 feet deep underground and is expected to burn over 200 more years.
The reason the fire in Centralia can't be put out is because it's too hot and too deep to be fought effectively so it can't be put out and must be left to burn.
Centralia is a nightmare of unstable ground and dangerous fumes and as a result the town is condemned, and toxic gas may rise from the ground at any time.
When the coal was originally mined, a few pillars of coal were left intact to prevent the ground above from collapsing into the mine.