How did baseball’s milestone marks get created?

Specifically, why is a player’s 3000th hit such a big deal, and when did it become one?

Over the next couple of weeks, Alex Rodriguez will provide an excellent example of the arbitrariness of the career milestones that occasion different levels of media attention.

Rodriguez is about to drive in his 2000th run. He will be only the third player, after Aaron and Ruth, to do so (if you don’t count Cap Anson’s years in the National Association as major league stats, which I don’t because he was a bad guy).

Meanwhile, he’s also about to become the 29th player to get 3,000 hits. The latter achievement is going to get a lot more media attention, because somewhere in the distant past (apparently shortly after Sam Rice retired while 13 hits short) 3,000 hits became The Official Mark of Baseball Greatness. How and when did this happen?

A similar thing happened (quite a bit later I’m guessing, since only two three players had reached the mark prior to 1960) with 500 home runs. In the pre-internet days, when we had to walk five miles to school through six-foot snowdrifts, and baseball statistics were primitive and hard to come by, those were the two milestones that counted. (For pitchers it was and remains 300 wins, probably because 300 is 3000 divided by ten).

Relatedly, I was a fanatical baseball fan and something of a baseball stats geek as a teenager in the 1970s, and I literally don’t remember hearing anything about Aaron passing Ruth to become the all-time RBI leader, which according to the record books happened sometime early in the 1975 season (Of course Aaron’s 715th home run the year before was one of the biggest sports stories ever).

A side issue in all this is the extent to which the steriod era has or is going to destroy the magic of 3000/500 in the mind of the members of the BBWA, who control the politics of glory, in re the Hall of Fame.

. . . in comments, several people argue that RBI are context-dependent in a way that hits aren’t, and that therefore the career hits leaderboard is a better measure of greatness than the list of career RBI men. Except:

Top ten RBI leaders who aren’t in the 3000 hit club:

Ruth
Bonds
Gehrig
Foxx
Ott
Williams
Griffey
Ramirez
Al Simmons
Frank Robinson

Top ten hits leaders who aren’t in the top 29 in career RBI (equivalent to career 3000 hit list):

Rose
Speaker
Jeter
Molitor
Eddie Collins
Lajoie
Brett
Waner
Yount
Gwynn

Obviously the second group is made up of great players, but just as obviously career RBI is a better proxy for all-time greatness than career hits.