A Data Driven Exploration of Chess Link

From Randal Olson:

Chess games have in fact steadily become longer since 1970, increasing from 75 ply (37 moves) per game in 1970 to a whopping 85 ply (42 moves) per game in 2014. Furthermore, if the current trend holds, chess games will only keep getting longer as time goes on.

This is a pretty interesting use of historic data on chess matches.