Clear answer: There are no known surface or active volcanoes in Illinois.
Know that a search for “Volcanoes in Illinois” returns nothing that fits the usual meaning of a volcano. Illinois has no mountains of lava, no volcanic cones, and no recorded eruptions. Authoritative surveys (USGS and the Illinois State Geological Survey) list no modern or historic volcanoes inside the state.
Understand why this is so. Illinois sits in the middle of a stable continental interior, far from plate boundaries and hotspot tracks that make volcanoes. The state is covered by thick layers of sedimentary rock and glacial deposits. Any igneous activity that did occur is very old and mostly buried deep beneath younger rocks. That is why no visible volcanoes meet the keyword criteria.
Explore close matches instead. Ancient igneous events left traces nearby, not surface volcanoes in Illinois. Examples include the Midcontinent Rift volcanic rocks around Lake Superior and the very old St. Francois Mountains igneous rocks in southeastern Missouri. The nearest regions with active volcanoes are far to the west and south—the Cascade Range (Mount St. Helens, Mount Rainier) and volcanic zones in Mexico (Popocatépetl). For this topic, examine Illinois’ buried igneous rocks, local outcrops, and the geology of nearby volcanic provinces.
