There are fewer than 20 bats known to be left in existence that were once used by the record-setting player. Gehrig can be seen holding the bat at Comiskey Park in 1930, one of his best ever seasons.

Bidding began at $20,000 (18,250 euros) at the auction on Sunday morning by Love of the Game Auctions. After 46 bids, the price reached $436,970, beating the $403,000 record reached in 2011 for the bat with which Gehrig hit his last home run in 1939.

Auctioneer Al Crisafulli explained how it had come to be sold: "This bat was given to the consignor decades ago by a family member of a former Yankee Stadium groundskeeper," Crisafulli said. "Though the consignor is a Yankee fan, the family is not a baseball family, and without knowledge of the bat's value it was kept behind the front door for protection - for 30 years."

"Really, it is amazing that this outstanding piece of memorabilia made it this far, and its history certainly adds color to the story," Crisafulli added, noting that it was nearly left behind when the seller moved house fifteen years ago. A few years later it was almost given to a neighbor's child who liked playing ball.

On the bat itself, Crisafulli said: "All that aside, it is gorgeous. It is important. And it is among the most exciting consignments with which an auction house can be entrusted." The Batrite model bat was made by Hanna Manufacturing in Athens, Georgia.

'Like a fingerprint'

The auctioneer was able to track its authenticity through a newspaper photograph of Gehrig with Babe Ruth and Bob Shawkey at Comiskey Park in 1930. Gehrig was clearly holding the Batrite bat. From the image Crisafulli was able to match the grain on the bat to the one he had at his auction house.

"The wood grain on each bat is like a fingerprint," Crisafulli said. "The grain on every bat is unique, much like the pinstripes on every jersey."

The 1930 season was one of Gehrig's finest. With a .379 batting average, he hit 41 home runs and 173 runs batted in. In the 13 seasons between 1926 and 1938, the player named the "Iron Horse" drove in at least 109 runs each season.

Gehrig's career was cut short in 1939 by an illness later diagnosed as amyotrophic lateral sclerosis, which became known as "Lou Gehrig's Disease," and he died in 1941.