The deadliest tornado in recorded U.S. history occurred 100 years ago. The Tri-State Tornado touched down in southeastern Missouri on March 18, 1925.

Deaths were reported in Kansas, Mississippi, Arkansas, Texas and Missouri as dozens of tornadoes ripped through the United States.

A new tornado watch was issued Sunday for parts of West Virginia, Ohio and PA. 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 moving east.

At least 36 people have died across seven states as powerful storm systems swept through the Midwest and South. The storms have left hundreds of thousands of customers without power, injured dozens in Arkansas and caused fatalities linked to wildfires in Oklahoma.