Communities across Missouri, Illinois, and Indiana were devastated by the deadliest and longest-running tornado ever recorded a century ago. Here's what happened.

A deadly tornado outbreak ripped through Missouri, Illinois, Arkansas and Mississippi overnight Friday, leaving destruction, power outages and tragic loss in its wake.

The deadliest twister in recorded U.S. history struck 100 years ago Tuesday, touching down in southeastern Missouri and tearing up everything in its 219-mile (352-kilometer) path for nearly four hours through southern Illinois and into Indiana.

Millions of Americans across the country are on alert for a severe weather outbreak as violent, long-track tornadoes with damaging winds of up to 80 mph and large hail are expected across the Midwest and South with the cross-country storm moveing east.

Meanwhile, the severe weather threat will linger through Sunday from Florida northward into the upper Ohio River Valley, forecasters warned.

Unusually vicious and damaging weather across multiple U.S. states spawned violent tornadoes, blinding dust storms and fast-moving wildfires over the weekend, leaving at least 39 people dead. In the latest tally of the destruction,