Just short of 20 years ago, Reggie Jackson hit the 563rd home run of his 21-year career. That was the last home run he hit, and he finished that season as one of only 14 players with at least 500 career homers. From 1920 -- roughly speaking, when players actually began to hit home runs -- through 1987, there were only 14 players with 500 homers.

Frank Thomas just hit his 500th homer, which means that in the 20 years since Jackson took his last swing, membership in the 500 Club has increased by 50 percent, from 14 players to 21. And by the end of the 2008 season, it's likely five more members will have joined. Alex Rodriguez (492) isn't far behind Thomas. Jim Thome (482) and Manny Ramirez (481) are locks to reach 500, and Gary Sheffield (472), given even just reasonable health, will clear 500 next summer.

Jackson is in the Hall of Fame, and so are the 13 players before him who reached 500 homers. More than nine years passed before another player joined Jackson; in 1996, Eddie Murray hit his 500th, and he has a plaque in Cooperstown, too. That made the 500 Club 15-for-15 in the Hall of Fame.

Frank Thomas, right, is the 21st player in history to hit 500 home runs.
Lately, though? Not so much. Mark McGwire hit 583 homers and got barely a sniff from Hall of Fame voters in his first try this year. Granted, there were extenuating circumstances. But many voters claim McGwire isn't Hall-worthy even without those circumstances.

So, is 500 the new 400?

At the moment, there are 12 Hall of Fame-eligible players with between 400 and 499 home runs. Of those 12, eight have been elected to the Hall, leaving four who have not: Darrell Evans (414), Andre Dawson (438), Dave Kingman (442) and Jose Canseco (462).

Would Canseco be in the Hall of Fame if he'd hit 38 more home runs? Almost certainly not, and for reasons that have little to do with his various other statistics. Extenuating circumstances, you might say. What about Kingman, though? He hit 35 homers in his last season, and was only 37. If he'd been a little easier to get along with, he might well have hung around for a couple of seasons more and topped 500 home runs. Would he be in the Hall today? Probably not.

So, was 500 a magical number and 400 a nonmagical number? Or was 400 simply a less magical number? Or are there perhaps no magical numbers at all?

Let us consider the four members of the 500 Club in lowest standing: Ernie Banks (512), Eddie Mathews (512), Mel Ott (511) and Murray (504). Mathews had to wait for too long (five years) for his election to the Hall of Fame, but does anyone care to argue that any of these players would not be Hall of Famers if they'd fallen short of 500?

The next four ahead of them: Ted Williams, Willie McCovey, Jimmie Foxx and Mickey Mantle. You might not have known that each of those Hall of Famers hit more than 500 home runs, but you probably know that each of them rank among the all-time greats at their respective positions. And this would be true whether they hit 521 homers (as both McCovey and Williams did) or 481.

Do 500 home runs mean more in the minds of the voters than 499 home runs? Sure, probably a little bit more, particularly in the minds of the little-minded voters. Most of them, though, are smart enough to consider a player's home runs, whether 521 or 481, in context with the rest of that player's career.

So when Thomas hit his 500th home run, did he go from Cooperstown wannabe to Hall of Fame lock? No. Thomas was, in the collective mind of the voters, a marginal candidate yesterday and remains a marginal candidate today. Remember, though, the voters are getting smarter all the time. His career OPS ranks 11th of all time, and when Thomas becomes Hall-eligible in eight or 10 years, many of the voters will actually know what OPS means. Remember, too, that he's not finished padding his stats yet.

Hitting 500 home runs doesn't hurt. Every little bit helps, and No. 500 might even be a big bit. But it's just a bit. And that is what it always has been.