How many turns does an average game of Checkers/Draughts go for?
The American Checker Federation

The ACF has the transcripts for a lot of games. By my count, they have 9,374 games recorded from 1952 to 2009. These are available for download. In these 10k games, there has been 460,381 moves made. Thus an average* game of checkers takes 49.11 moves or 24.56 moves per color. 

Here is a summary:

White Wins:  1596
Draw:        5406
Black Wins:  2372
-----------------
Total Games: 9374

Total Moves:      460381
Moves/Game:       49.11
Moves/Game/Color: 24.56


* average game between two ACF players