The most powerful earthquakes in the history of the United States happened along the New Madrid Fault in 1811 and 1812. Those earthquakes were reportedly felt more than 1,000 miles away. Scientists assure us that one day we will once again see very powerful earthquakes along the New Madrid fault. It is only a question of when it will happen. Today, the New Madrid fault zone covers portions of Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee and Mississippi. However, a major earthquake of magnitude-8.0 or greater would likely have a dramatic effect all the way from the Great Lakes all the way down to the Gulf of Mexico.