The Wikipedia entry has been updated for the Super Outbreak, and I don't know about anyone else, but reading some of this actually sent chills up my spine:
The Super Outbreak is the second largest tornado outbreak on record for a single 24-hour period. From April 3 to April 4, 1974, there were 148 tornadoes confirmed in 13 US states, including Illinois, Indiana, Michigan, Ohio, Kentucky, Tennessee, Alabama, Mississippi, Georgia, North Carolina, Virginia, West Virginia, and New York; and the Canadian province of Ontario. It extensively damaged approximately 900 square miles (2,330 square kilometers) along a total combined path length of 2,600 miles (4,160 km).
The Super Outbreak of tornadoes of 3–4 April 1974 remains the most outstanding severe convective weather episode of record in the continental United States. The outbreak far surpassed previous and succeeding events in severity, longevity and extent. With a death toll of over 300, this outbreak was the deadliest since the 1925 Tri-State Tornado and its associated outbreak until the April 25–28, 2011 tornado outbreak, which killed at least 318 people.