The Minnesota Twins are a Major League Baseball franchise based in Minneapolis, Minnesota. They play in the American League Central division. Also known in their early years as the "Washington Senators" (1901–1960) based in Washington, D.C., pitchers for the Twins have thrown seven no-hitters in franchise history. A no-hitter is officially recognized by Major League Baseball only "when a pitcher (or pitchers) allows no hits during the entire course of a game, which consists of at least nine innings", though one or more batters "may reach base via a walk, an error, a hit by pitch, a passed ball or wild pitch on strike three, or catcher's interference". No-hitters of less than nine complete innings were previously recognized by the league as official; however, several rule alterations in 1991 changed the rule to its current form. A perfect game, a special subcategory of no-hitter, has yet to be thrown in Twins history. As defined by Major League Baseball, "in a perfect game, no batter reaches any base during the course of the game." Walter Johnson threw the first no-hitter in Senators/Twins history on July 1, 1920; the most recent no-hitter was thrown by Francisco Liriano on May 3, 2011. Four left-handed pitchers have thrown no-hitters in franchise history while three were by right-handers. The longest interval between no-hitters was between the games pitched by Bobby Burke and Jack Kralick, encompassing 31 years and 8 days from August 8, 1931 to August 26, 1962. Conversely, the shortest interval between no-hitters was between the games pitched by Kralick and Dean Chance, encompassing 4 years and 364 days from August 26, 1962 to August 25, 1967. They no-hit the Boston Red Sox the most, which occurred twice, which were no-hit by Johnson in 1920 and Burke in 1931. There is one no-hitter in which the team allowed at least a run, thrown by Chance in 1967. The most baserunners allowed in a no-hitter were by Chance (in 1967) and Liriano (in 2011), who each allowed six. Four no-hitters were thrown at home, and three were thrown on the road. They threw one in April, one in May, one in July, three in August, and one in September. Of the seven no-hitters, three have been won by a score of 1–0, more common than any other results. The largest margin of victory in a no-hitter was a 7–0 win by Eric Milton in 1999.