And the cards are in superb condition.
Experts say it's one of the biggest, most exciting finds in the history of sports card collecting.
Two cousins came across the cards from 1910 in a soot-covered box last February in the Ohio town of Defiance. They say the cards belonged to their grandfather, who died in the 1940s.
The best of the bunch - 37 of the 700 or so cards - are expected to bring a total of $500,000 when they are sold at auction in August.