In 1973 the American league adopted the designated hitter rule in an effort to increase scoring. The American league expanded to 14 teams in 1977. Major League Baseball expanded again in 1993, when the national league added two new teams. Club owners and players agreed to a realignment of the league structure in 1994. Under this realignment, each league grouped its 14 teams into three separate divisions. In an attempt to draw more fans, Major League Baseball insitituted interleague play in 1997, matching AL and NL teams against each other in a limited number of regular-season games. These interleague matchups were previously confined to spring trainning and the World Series. Designated hitters appeared in NL lineups in games held in AL ballpark, and AL pitchers batted during games at NL parks. Interleague play also was intended to foster local rivalries. Another expansion took place in 1995 as MLB capitalized on the growing population of baseball fans in the Sun Belt by establishing the Tampa Bay Devil Rays in Saint Pertersburg in Florida, and the Arizona Diamondbacks in Phoenix, the team that won the 2001 World Series. Those two clubs began playing in 1998. The expansion necessitated a minor realignment of the leagues and divisions, however. In a deal brokered by franchise owners and MLB, the Milwaukee Brewers left the AL and joined the NL Central Division before the 1998 season, thereby becoming the first team in modern professional baseball to switch leagues.