List of North American tornadoes and tornado outbreaks

These are some notable tornadoes, tornado outbreaks, and tornado outbreak sequences that have occurred in North America. Where applicable, a count of the number of significant (F2/EF2 and stronger), violent (F4/EF4 and stronger), and killer tornadoes is included for outbreaks.
 * 1) The listing is U.S.-centric, with greater and more consistent information available for U.S. tornadoes. Some North American outbreaks affecting the U.S. may only include tornado information from the U.S.
 * 2) Exact death and injury counts are not possible, especially for large events and events before 1950.
 * 3) Prior to 1950 in the United States, only significant tornadoes (rated F2 or higher or causing a fatality) are listed for the number of tornadoes in outbreaks. These ratings are estimates from tornado expert Tom Grazulis and are not official.
 * 4) Due to increasing detection, particularly in the U.S., numbers of counted tornadoes have increased markedly in recent decades although number of actual tornadoes and counted significant tornadoes has not. In older events, the number of tornadoes officially counted is likely underestimated.
 * 5) Historical context: Much of the tornado activity in the American Midwestern area is relatively unknown and significantly under-reported prior to the middle of the 1800s as few people lived there to record the yearly activity. The American government did not acquire the Midwestern states area until the 1803 Louisiana Purchase from the French government. The Louisiana Purchase area included major tornado activity areas of north Texas, Oklahoma, Kansas, Nebraska, Arkansas, Missouri, Iowa, South Dakota, and lower Minnesota. Large groups of settlers and pioneers only began populating the region after 1820. As these areas began being more populated, existing tornado activity there became more known and reported through newspaper and telegraph.