The town celebrated it as Coolidge Day because (so all the civic boosters said, and apparently believed) President Calvin Coolidge had dedicated the town library on this day in 1926. It was true; he had dedicated the library here (in 1925, though).
But the first Coolidge Day was actually celebrated in 1870, in honor of local schoolteacher Hepzebah Coolidge, who ended her three-decade career on a bad note that year by burning down the home of the mayor, with whom she'd had a torrid but unrequited affair for 22 years. Miss Coolidge was an institution.