The Tri-State tornado of March 18, 1925 is the deadliest tornado in US history, killing at least 695 people as it traveled 219 miles across Missouri, Illinois, and Indiana over roughly three and a half hours. No single tornado before or since has produced a longer confirmed path, a longer continuous duration, or a higher death toll on American soil.
The tornado first touched down at approximately 1:01 PM in Ellington, Missouri, and lifted near Petersburg, Indiana around 4:30 PM. Its forward speed averaged an extraordinary 62 mph — nearly twice the typical tornado forward speed — with peaks estimated at 73 mph. The path width ranged from ¼ mile to over 1 mile.
Because the storm predated the Fujita scale (introduced in 1971) and the Enhanced Fujita scale (2007), it has no official rating. Modern analyses by tornado researchers, including reconstructions using surviving damage photographs and eyewitness accounts, generally place it at F5 / EF5 intensity, with sustained damage consistent with winds above 260 mph.
Some of the highest death tolls:
Total damage was approximately $16.5 million in 1925 dollars — equivalent to roughly $1.9 billion in today's terms.
Several factors combined to produce the catastrophic death toll:
The Tri-State tornado led directly to the beginnings of organized severe weather forecasting in the United States. It remains the benchmark against which all subsequent long-track violent tornadoes are compared — no confirmed single-funnel tornado since has come close to its 219-mile path length or its 695-death toll.
Some modern researchers have argued the Tri-State event may have been a "tornado family" of several successive funnels rather than a single continuous vortex; the 2013 analysis by Maddox et al. defended the single-tornado hypothesis using damage-track continuity.
→ Simulate a Tri-State-scale long-track tornado