Thursday showers and a few storms are looking possible here, coming on a day that also recognizes the anniversary of the deadliest tornado in U.S. history.

The Tri-State tornado that moved through three states in the central United States. It started in Missouri, moved through southern Illinois, then into southwestern Indiana. It killed at least 695 people, making it the deadliest in U.S. history, and the second deadliest in world history.

The tornado was rated an F5, the strongest on the Fujita scale. It first touched down shortly after 1:00 p.m. local time in Shannon County, Missouri on the 18th. It was on the ground for over three and a half hours, lifting after 4:39 p.m. in Petersburg, Indiana.

After the storm, over 2,000 people were left injured and nearly 700 were killed. It’s estimated that there was over $2.2 billion dollars in damage.

This makes it by far the deadliest tornado in U.S. history. The second deadliest in U.S. history killed 317 people in May of 1840 during the “Natchez Tornado” which hit parts of Louisiana and Mississippi.

The deadliest tornado in the state of Texas’ history was a tornado that hit Waco in May of 1953, leaving 114 people dead.