Broward County Commissioner John Rodstrom discovered the stamp, which may be the famous Inverted Jenny, while reviewing absentee ballots.
There was no name on the envelope, so the vote did not count.
What seemed like a small stamp collection on one envelope caught Rodstrom's eye. At least one was from 1936, Rodstrom said. Then he noticed one had an upside-down World War I-era airplane — the hallmark of an "Inverted Jenny."
"I was a stamp collector when I was little," Rodstrom told The Miami Herald. "I recognized it."
Rodstrom discussed the stamp with the other members of the canvassing board — Broward County Court Judge Eric Beller and the supervisor of elections.
A stamp-collecting Broward Sheriff's Office deputy overheard them talking about the possible Jenny. After hearing the description, he said the stamp would be very valuable if it was real.
But it was too late.
"By that time we had already sealed the box. And once you seal the box, under the election law you can't unseal it," Beller said. "We looked at the election law to see if we could unseal it, and we didn't think we could."
The 24-cent Jenny stamps were printed in 1918, said Maynard Guss, president of the Sunrise Stamp Club. Stamp sheets were run through presses twice to process all the colors, and on one pass, four Jenny sheets went through backward, Guss said. Inspectors caught the errors on three of the sheets and destroyed them, but somehow, a sheet of 100 stamps got through.
Stamp collectors have spent the past 88 years trying to find them all. Replicas are sold on Web sites like eBay.
But this Jenny, if real, might not be as valuable as it could have been. When the absentee ballot was mailed the stamp was canceled, reducing its value, Rodstrom said.