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The Death and Life of the 13-Month Calendar

Favored by leaders in transportation and logistics, the International Fixed Calendar was a favorite of Kodak founder George Eastman, whose company used it until 1989.
relates to The Death and Life of the 13-Month Calendar
George Eastman House

In a scalding-hot argument against the 12-month calendar, a September 1927 issue of The Outlook proclaimed:

Momentum behind the International Fixed Calendar, a 13-month calendar with 28 days in each month and a leftover day at the end of each year (it also followed the Gregorian rules with regards to Leap Years), was never stronger than in the late 1920s. Similar to Auguste Comte's positivist calendar (created in 1849), this particular 13-month invention came from the mind of Moses Cotsworth, a North Eastern Railway advisor bothered by inexplicably varying monthly earnings over the traditional 12-month period. Cotsworth's plan quickly gained popularity among businessmen, especially in transportation and logistics. His biggest ally however, was photography pioneer and Kodak founder, George Eastman.