At Fenway Park, the Yankees beat the Red Sox in the nightcap to complete a day-night doubleheader sweep. The 14-11 slugfest, in which the Al East Division rivals bang out a total of 34 hits, takes 4 hours and 45 minutes to play, making it the longest nine-inning game in big league history. A team scores in nine of the 18 half-innings.

On August 18, 2006 — At Fenway Park, the Yankees beat the Red Sox in the nightcap to complete a day-night doubleheader sweep. The 14-11 slugfest, in which the Al East Division rivals bang out a total of 34 hits, takes 4 hours and 45 minutes to play, making it the longest nine-inning game in big league history. A team scores in nine of the 18 half-innings.

Source:
Baseball Reference August 18
National Pastime
Retro Sheet
Hall of Fame
SABR Games Project
Replay The Game