Jason LeBlanc of Newburyport bought a 1865 Brooklyn Atlantics card Wednesday for $92,000 at the Saco River Auction Co. in Biddeford, Maine, the Portland Press Herald reported Thursday.
The card, which may be the last of its kind, was found by an antiques picker in Baileyville, Maine, last year.
LeBlanc said the card is an investment for his 4-year-old son, Alex, whose health problems require frequent hospital stays. The boy's mother died after giving birth, LeBlanc said.
"Alex is everything to me, and this is something I hope pays off," the father said.