Good question! (I’m looking at you Mr. Jindal…)
Here’s a list compiled a few years back from Volcanoes of North America: United States and Canada, by Wood and Kienle. They list all volcanoes that are younger that 5 million years old and are morphologically distinct. If your state is not listed it probably means there are no volcanoes there or they are the remnants of something older than 5 million years! (let the floods commence)
According to them, there are about 262 volcanoes and volcanic fields in North America.
|Location||Number of Volcanoes|