I was going to add this, but I see that it's already here.  With smaller ballparks and many power hitters not particularly swift afoot, "Wahoo"'s record will never be broken.  He also holds the single season record for most inside-the-park home runs with 12 in 1901.

309 triples? WOW! Triples are probably one of the hardest things to hit in baseball. Takes alot of speed and power. Amazing!

  It would be very, very hard to beat this barring some extremely radical changes to the game. 20 triples in a season is very hard to do now, though it does occur every now and again. You'd have to do that for about 16  seasons. The parks aren't as cavernous as many of them were in Crawford's day.

Crawford was a terrific dead ball era player for Cincinatti and ( mostly) Detroit- solid in every aspect, who was somewhat overshadowed by his teammate Ty Cobb, and stars of the time like Lajoie, Speaker, Wagner, and Eddie Collins but a worthy Hall of Famer

Few records speak as clearly to the evolution of the game as this one.

Crawford played from 1899 to 1917, and was a fine ballplayer, and a eminent member of the Hall of Fame. During much of this period, triples and not home runs were the truer measure of a hitter's power, as ball-parks tended to have expansive outfields.

The most triples by a player who played his entire career after the Second World War is 166 by Roberto Clemente.

This record will stand forever unless we see a return to immense unbounded outfields.