1925. There were 794 tornado deaths in the U.S. that year, 695 from a single tornado.
The Tri-State tornado of March 18, 1925. The tornado killed 695 people, 613 of them in Illinois.
The last F5 or EF5 tornado to hit the United States was on May 20, 2013 in Moore, Oklahoma. The last U.S. tornado to be rated F5 on the original Fujita scale (though EF5 is essentially the same rating) was the Bridgecreek-Moore, Oklahoma tornado of May 3, 1999.
As of January 17, 2013 the last tornado in the U.S. was an EF1 near Poplarville, Mississippi on January 13. It was one of four weak tornadoes to occur in the southern U.s. that day.
The first recorded tornado in the US was in Rehoboth, Massachusetts in August of 1671.
The worst (or at least the deadliest) tornado to hit the U.S. was the Camilla, Georgia tornado of February 13, which killed 11 people.
Probably Alabama
The worst tornado in U.S. history was the Tri-State tornado of March 18, 1925. The tornado first formed north of Ellington, Missouri. The tornado devastated numerous towns in Missouri, Illinois, and Indiana along a path 219 miles long.
The longest-lived and farthest traveling tornado was the world in the US, but not in the world. It was the Tri-State tornado of March 18, 1925, which hit portions of Missouri, Illinois, and Indiana. The worst tornado on record in the world was the Daulatpur-Saturia tornado, which struck central Bangladesh on April 26, 1989.
Spring is when the U.S. generally has the worst tornadoes.
The worst tornado of 2012 would probably be the EF4 tornado that hit the towns of Henryville, New Pekin, and Marysville in Indiana on March 2, killing 11 people.
The worst tornado to hit Cowley County Kansas was the Udall, Kansas F5 tornado of May 25, 1955. This tornado killed 80 people, making it the deadliest tornado in Kansas history.
The worst tornado that came to Earth was in daultapur salturia Bangladesh of April 26 1989 killed more than 1300 people
1925. There were 794 tornado deaths in the U.S. that year, 695 from a single tornado.
The worst tornado in U.S. history caused damage in Missouri, Illinois, and Indiana. The worst tornado in world history (the Daulatpur-Salturia tornado) occurred in Bangladesh so it did not hit any states per se.
The Woodward, Oklahoma tornado of April 9, 1947 with 181 deaths.
By far the worst tornado to hit the U.S. in 2011 was the Joplin, Missouri tornado of May 22. This tornado was rated EF5, the highest level of tornado intensity. 30% of the city of Joplin was destroyed. In total the tornado killed 158 people (in addition to several indirect deaths), injured over 1,100 , caused $2.8 billion in damage, and destroyed nearly 7,000 homes. This makes it the costliest and 7th deadliest tornado in U.S. history.