Early on the morning of Dec. 16, 1811, the ground in the New Madrid area began to lurch, and for a few minutes the Mississippi River in places ran backward. Eliza Bryan, who lived through the shock, described a violent earthquake with a noise like loud, distant thunder and said the river’s current was retrograde.

That is why the New Madrid earthquakes still pull readers in today: they were not just a strange river story, but a sequence of powerful shocks that changed a river and rattled a huge swath of the country. Otto Nuttli later estimated the first quake at about 7.2 on the body-wave magnitude scale, with major shocks following on Jan. 23, 1812, and Feb. 7, 1812.

The destruction went far beyond the small settlement that gave the quakes their name. New Madrid was severely damaged, boats on the Mississippi reported the river running backward in parts during the last earthquake, and whole communities shifted into tents as the ground kept rumbling. Landslides spread across 125 miles of bluffs on the east side of the Mississippi, and the effects reached places that seem far removed from the river valley: chimneys toppled in St. Louis, bells rang in Boston, and Dolly Madison was awakened in Washington, D.C.

Before modern seismology and plate tectonics, people often read quakes as acts of divine punishment, and the New Madrid sequence was among the strongest ever to hit the central United States. The closest city, St. Louis, was still about 150 miles away and had only about 5,700 people at the time, yet the region was hit hard enough to make the scale of the disaster hard to ignore.

The river’s reversal did not last. Tectonic uplifts likely dammed it in spots, probably through a fluvial tsunami, and it took days for the Mississippi to wind around the new obstructions. In the end, the most unsettling part of the story is not that the river turned for a moment, but that the land reshaped itself so forcefully that water had to find a new way through.