According to Wikipedia about 2hrs 45min:
In recent decades, observers have criticized professional baseball for the length of its games, with some justification as the time required to play a baseball game has increased steadily through the years. At the turn of the 20th century, games typically took an hour and a half to play. In the 1920s, they averaged just under two hours, which eventually ballooned to 2 hours and 38 minutes in 1960. Though in 1975, the average length of games was 2 hours 25 minutes, according to the Elias Sports Bureau. By the turn of the 21st century, games had got so long that Major League Baseball's goal in 2004 was to get the average game down to 2 hour and 45 minutes, after coming close in 2003 at 2 hours and 46 minutes.