When considering only the state of the board, and after taking into account board symmetries (i.e. rotations and reflections), there are only 138 terminal board positions. 

A combinatorics study of the game shows that when "X" makes the first move every time, the game outcomes are as follows:

• 91 distinct positions are won by (X)

• 44 distinct positions are won by (O)

• 3 distinct positions are drawn (often called a "cat's game")