The map, made between 1833 and 1835, labels a section of Pavilion Beach along Gloucester Harbor a "publick" beach.
Both the city of Revere and the state Department of Recreation and Conservation tout Revere Beach as America's oldest public beach.
It dates to 1896 - more than 60 years after the Mason map marked as public the spot where future generations of Gloucester residents would cheer Greasy Pole walkers and seine boat racers during the annual St. Peter's Fiesta.
Members of the Massachusetts Archive called the notation "interesting" but said they would need at least one more piece of documentation before handing America's Oldest Fishing Port the added title of Home of America's Oldest Public Beach.
"It's interesting that the map is marked that way," said Michael Comeau, an assistant state archivist.
Comeau said the state ordered maps made of every city and town in 1830. Gloucester's contribution, also a work of Mason's, is dated 1831, though Pavilion Beach is labeled only "beach."
John Hannigan, a reference archivist who looked at Mason's 1831 map, said it was not uncommon for map makers to reuse measurements and add details in later incarnations sold commercially.
He and Comeau said the later map could have used the same measurements as the officially commissioned 1831 map and been marked with greater detail.
The office of Mayor Thomas Ambrosino of Revere had no comment on the map or the possible challenge to the primacy of Revere Beach.
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