The most severe earthquake in recorded American history

The New Madrid earthquakes (a series of quakes starting on December 16, 1811, and lasting until March 1812) are considered to be the most severe earthquake event in United States history. It shook more than two-thirds of the United States and was felt in Canada. It changed the level of land by as much as 20 feet, altered the course of the Mississippi River, and created new lakes, such as Lake St. Francis west of the Mississippi and Reelfoot Lake in Tennessee. Because the area was so sparsely populated, no known loss of life occurred. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)