The 2017 All Star game roster size for each league was 18 in 1933, 20 in 1934, 25 in 1939, and 30 in 1982. On July 1, 2009, the MLB expanded from 32 to 33 players on each league's team roster.
On April 28, 2010, MLB announced several rules changes for future All-Star games, effective with the 2010 edition.
Rosters were expanded by one extra position player, to a total of 34.
The designated hitter will be used in all games, even in National League ballparks.
Pitchers who start on the Sunday before the game break will be replaced on the roster, but will still be recognized as All-Stars.
Each manager may designate a position player who will be eligible for game re-entry if the last position player is injured or ejected. This is in addition to a rule that allows a player to re-enter to replace an injured or ejected catcher.