View of the Mississippi River at Natchez, Mississippi, early 19th century.
May 6, 1840, 317 killed
After touching down about 20 miles (32 km) southwest of Natchez, Miss., the tornado quickly formed a path over the Mississippi River, likely contributing to the large death toll as the river was commonly flooded with regular boat traffic (one steamboat window flew 30 miles, or 48 km), transients and itinerant boatmen. The tornado was about 1 mile (1.6 km) wide, causing damage on both the Mississippi and Louisiana shores.