I started watching the Mets-Cardinals game this afternoon and a simple question started me off on a research project that kept me occupied for practically the whole game. My initial question was simply, why isn't Mark Mulder wearing #20 like he did in Oakland? I probably should have known that in St. Louis that jersey number belongs to Lou Brock. But that was enough to get me started thinking about retired numbers as a whole.

There's no rule when it comes retiring numbers. Some organizations have tons of them, like the Yankees and the Dodgers. Others (the Blue Jays, Mariners, Mets, Diamondbacks, Padres, and Rockies) have none. The Astros have retired six numbers in 42 years while the Cubs have retired three in more than a hundred. Milwaukee has retired the numbers of Rollie Fingers, who only spent five years as a Brewer, and Hank Aaron, who only spent two (though he spent many years in Milwaukee as a Brave). Tampa Bay retired Wade Boggs' #12 despite his not even playing two full years as a regular there.

Fingers and Aaron are two of the players to have the same number retired by two different teams. Oakland and Milwaukee hang Fingers' #34 while Atlanta and the Brewers honor Hammerin' Hank's #44. The Reds and the Orioles each have retired Frank Robinson's #20. The Red Sox and the White Sox both have a number retired for Carlton Fisk, but in mirror images: #27 and #72. Nolan Ryan's is the most retired jersey in baseball. The all-time strikeout king's #34 is honored in Arlington and Houston, and his #30 is retired by the Los Angeles California Angels of Anaheim.

Every number from 1 to 50 has been retired by at least one team except 13, 28, 31, 38, 43, 46, 47, and 48. The only numbers above 50 that have been retired are Don Drysdale's #53, Fisk's #72, and #85, retired in honor of former Cardinals owner Gussie Busch on his 85th birthday in 1984. #4 is the most-retired number overall (8 teams). The most popular double-digit retired number is 20 (7 clubs). Two wearers of retired numbers have MLBlogs -- Brooks Robinson (Orioles #5) and Tommy Lasorda (Dodgers #2).

Two retired numbers are "shared" by two players on the same team. The Expos/Nationals honor both Andre Dawson and Rusty Staub by taking #10 out of circulation, and two great Yankee catchers -- Bill Dickey and Yogi Berra -- split number 8. Besides Busch's #85, two other men who never wore a jersey have honorary numbers. Longtime Angels owner Gene Autry was given #26 in honor of his role as the 26th man on the roster, and the Marlins reserve #5 in memory of first team president Carl Barger, who died suddenly at the baseball winter meetings in 1992.

Only five men have been remembered exclusively for their work in the dugout as managers: Casey Stengel (Yankees #37), Walter Alston (Dodgers #24), Billy Meyer (Pirates #1), Fred Hutchinson (Reds #1), and Dick Howser (Royals #10). Only one coach has ever had his number retired: Jimmie Reese, the Angels' number 50. And of course every team sets #42 aside in honor of the sport's greatest hero, Jackie Robinson.

I could go on with this stuff for hours, but it's the bottom of the ninth in New York and the tying run is in scoring position. If anyone has any retired number stories or factoids they want to share, I'd love to hear them. Will Todd Helton be the first Rockies player to have his number retired? Which players who have left baseball in the past few years are due? I'd say Ryne Sandberg and Tony Gwynn are sure things. With great players moving around as much as they do now -- think Roger Clemens and Randy Johnson -- does it take less to qualify? We have to keep our standards reasonably high, or else all the players in the future will end up wearing fractions.