The May 2003 tornado outbreak sequence produced a total of 401 tornadoes from Colorado to the Middle Atlantic Coast of the United States and southern Ontario between April 30 and May 11, 2003. The twelve-day outbreak is the largest ever in the US since storm data was preserved in 1950. Overall, the outbreak was responsible for at least 42 deaths across five states with the majority of them during the busiest day on May 4, 2003 in which 39 were killed in Tennessee, Missouri and Kansas. There were also hundreds of injuries and extensive damage was reported across several areas.