Question: Which of the two tornado outbreaks killed the most people?
Context: The Tornado outbreak of May 1968 was a significant and deadly tornado outbreak that struck most of the central and southern United States from May 15 to May 16, 1968.  Producing 46 tornadoes, the outbreak killed at least 72 people, including 45 in Arkansas alone.  The outbreak also produced two F5s in Iowa.  It was one of the deadliest tornado outbreaks in the United States since the 1960s and is one of the deadliest outbreaks in Iowa history. The Tornado outbreak sequence of May 2004 was a series of tornado outbreaks that affected much of southern Ontario, the Central and Southern United States from east of the Rockies to the Mid-Atlantic States from May 21 to May 31, 2004.  Particularly hard hit were the central Plains from Missouri to Iowa and the Ohio Valley.  The Central Plains were hit by two significant outbreaks on May 22 and May 24, the first outbreak which produced a very large and violent tornado in Hallam, Nebraska.  The Ohio Valley was affected by one of the largest tornado outbreaks ever during the Memorial Day weekend on May 29–30. The tornado outbreak of February 23–24, 2016 was an unusually prolific late-winter tornado outbreak that resulted in significant damage across the southern and eastern half of the United States in late February 2016.  Lasting nearly a day and a half, the outbreak produced a total of 61 tornadoes across eleven states, which ranked it as one of the largest February tornado outbreaks in the United States on record, with only the 2008 Super Tuesday tornado outbreak having recorded more.  In addition, it was also one of the largest winter tornado outbreaks overall as well.  The most significant and intense tornadoes of the event were four EF3s that struck southeastern Louisiana, Pensacola, Florida, Evergreen, Virginia, and Tappahannock, Virginia.  Tornadoes were also reported in other places like Texas, Florida, and Pennsylvania.  Severe thunderstorms, hail and gusty winds were also felt in the Northeastern United States and Mid-Atlantic states on February 24 as well. The March 1913 tornado outbreak sequence was a devastating series of tornado outbreaks that affected the northern Great Plains, the Southern United States, and sections of the upper Midwest over a two-day-long period between March 21–23, 1913.  Composed of two outbreaks, the sequence first began with a tornado outbreak that commenced in Mississippi early on March 21.  Several significant tornadoes occurred, one of which killed seven people in one family and another destroyed much of Lower Peach Tree, Alabama, with 27 deaths all in that town.  The tornado at Lower Peach Tree is estimated to have been equivalent to a violent F4 tornado on the Fujita scale, based upon damage accounts.  The tornadoes occurred between 0630–1030 UTC, or pre-dawn local time, perhaps accounting for the high number of fatalities—a common trend in tornadoes in the Dixie Alley.  In all, tornadoes in Mississippi, Georgia, and Alabama killed 48 people, perhaps more, that day and injured at least 150 people. A tornado outbreak sequence, or tornado outbreak day sequence, sometimes referred to as an extended tornado outbreak, is a period of continuous or nearly continuous high tornado activity consisting of a series of tornado outbreaks over multiple days with no or very few days lacking tornado outbreaks. The Tornado outbreak sequence of May 1896 was a series of violent and deadly tornado outbreaks that struck much of the Central and Southern United States from May 15 to May 28, 1896.  It is considered one of the worst tornado outbreak sequences on record with tornado expert Tom Grazulis stating that the week of May 24–28 was "perhaps the most violent single week of tornado activity in US history".  There were four particularly notable tornado outbreaks during the two-week period.  It produced three F5 tornadoes as well as the third deadliest tornado ever in United States history.  A total of 484 people were killed during the entire outbreak sequence by at least 38 different tornadoes which struck Texas, Oklahoma, Kansas, Nebraska, Illinois, Missouri, Iowa, Kentucky, and Michigan. On March 2 and 3, 2012, a deadly tornado outbreak occurred over a large section of the Southern United States into the Ohio Valley region.  The storms resulted in 41 tornado-related fatalities, 22 of which occurred in Kentucky.  Tornado-related deaths also occurred in Alabama, Indiana, and Ohio.  The outbreak was the second deadliest in early March for the U.S. since official records began in 1950; only the 1966 Candlestick Park tornado had a higher death toll for a tornadic system in early March. The 2012 Leap Day tornado outbreak was a tornado outbreak on February 28 and February 29, 2012.  It caused severe damage in several regions especially in the Ohio Valley region.  It also resulted in several tornadoes in the Central Plains, a rarity for the time of year.  The most destructive tornado hit Harrisburg, Illinois, killing 8 people in one neighborhood.  In total, 15 people died in the outbreak.  Just two days later, a larger and deadlier outbreak occurred across the eastern and southern United States. The tornado outbreak sequence of May 22–31, 2008 was a series of tornado outbreaks affecting the central plains of the United States since May 22 to May 31 of 2008.  It was also one of the largest continuous tornado outbreaks on record.  A total 239 tornadoes were confirmed, with the most intense activity occurring across the Great Plains.  One person was killed when a large wedge tornado struck Windsor, Colorado, and two more deaths were reported in Pratt County, Kansas.  One person was also killed near Hugo, Minnesota on May 25 and nine were killed by an EF5 tornado that destroyed most of Parkersburg, Iowa and a small subdivision of New Hartford, Iowa (located near Waterloo, Iowa).  Another death, caused by lightning related to the storms, took place in central Kansas. The 1984 Soviet Union tornado outbreak, also known as the 1984 Ivanovo tornado outbreak, was one of only three disastrous tornado outbreaks in modern Russian history (one of the others being the 1904 Moscow tornado) and the third-deadliest tornado outbreak in European history.  Occurring on June 9, 1984, the outbreak struck the Ivanovo and Yaroslavl regions north of Moscow, an area over 400,000 km.  At least two of the eleven known tornadoes were violent events, equal to F4 or F5 in intensity on the Fujita scale, based upon observed damages.  The deadliest single tornado was posthumously rated at F5 intensity and killed at least 92 people along its long path near Ivanovo and other towns.  The tornado, up to 800 m wide, caused extreme damage, reportedly annihilating steel-reinforced concrete structures and throwing heavy objects of 320000 kg for distances up to 200 m .  Another tornado, assessed to have been at least F4 and possibly F5 in intensity, occurred at Kostroma.  Severe thunderstorms also produced hail up to 1 kg in weight, among the heaviest hailstones confirmed worldwide.  In all, the entire tornado outbreak killed at least 400 people and injured 213.
Answer: March 2 and 3, 2012