For the first time in Major League Baseball history, teams from the American League and National League competed in regular season, head-to-head competition during the 1997 campaign. The first Interleague game was on June 12 as the Texas Rangers hosted the San Francisco Giants at The Ballpark in Arlington.
For the first five seasons of Interleague Play, each division played against the same division from the other league (NL East vs. AL East, NL Central vs. AL Central and NL West vs. AL West). As of the 2002 season, a new format to Interleague Play was instituted where teams play Interleague games against various divisions.
During Interleague Play the designated hitter rule is used in all American League ballparks, but is not used in National League stadiums, which is how the DH is used in World Series play. From 1997-99, umpire crews for each Interleague game came from the league where the game is being played.
The following is text of Major League Baseball's policy regarding the compilation of statistics as a result of Interleague Play:
"For the first time in the history of Major League Baseball, Interleague games are to be played during the regular season. Breaking tradition always brings about controversy and the matter of baseball records is no exception.
"It is the opinion of Major League Baseball that there is no justification for compiling a new volume of records based on Interleague Play. On the contrary, the sovereignty of each league's records will be retained, and if a player or a team breaks a record against an Interleague opponent it will be considered a record in that league. In cases where two teams -- as Interleague opponents -- break a league or Major League record, that record will be annotated with the phrase 'Interleague game.' Streaks by both teams and individual will continue (or be halted) when playing Interleague opponents in the same manner as if playing against an intraleague opponent. In essence, records will be defined by who made them rather than against whom they were made.
"The official statistics of both leagues will be kept separately as they have in the past. This means statistics for each team and their individual players will reflect their performance in games within the league and also in Interleague games without differentiation."
RECORDS, LEADERS, STATS