What is officially the highest scoring pro baseball game of all-time?”
The highest scoring game in major league history took place on August 25, 1922: the Chicago Cubs defeated the Philadelphia Phillies 26–23, a total of 49 runs. The record for most runs scored by a team in a single game in the modern baseball era (1901 and later) is 30, set on August 22, 2007 by the Texas Rangers against the Baltimore Orioles in the first game of a doubleheader at Oriole Park. The Rangers scored 5 runs in the fourth inning, 9 in the sixth, 10 in the eighth, and 6 in the ninth. The all time record for most runs scored by a single team in a game is 36, set by the Chicago Colts (now the Chicago Cubs) against the Louisville Colonels (which joined the National League in 1892) on June 29, 1897.
