MLB extra inning information for regular season games exists here from the 1954 season forward.

For the NBA reglar season games, all NBA overtime information exists here from the 1974-75 season forward, and some of the earlier overtime games are listed. All playoff games have the number of overtimes listed.

College basketball before 1979-80 only includes the NCAA Tournament games, and overtime games are complete only back through the 2003-04 season.

The NBA neutral games don't match the neutral game won-loss records found in Sporting News NBA guides.
These are being annotated here.