By Chris Daly
Union Square Rally, 1912 (Library of Congress)
Now, we have the answer — or at least, an answer — from the reliably delightful Robert Krulwich. The culprit: Dwight Eisenhower, who did in fact wear hats from time to time. Ike’s role in eliminating the hat was more roundabout, according to Krulwich. Ike is credited with launching the Interstate Highway system,which made the automobile the No.1 way of getting places. The automobile, in turn, actually did in the hat, because the typical car does not have enough room above the occupants’ heads to accommodate a real hat.
Seems plausible enough to merit a hat-tip for Krulwich.
Prof Chris Daly's Blog 
One theory I had heard about the demise of men’s hats attributed it to Eisenhower’s successor, John F. Kennedy who didn’t wear a hat while in office.
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I believe that the Kennedy policy is the standard interpretation. That’s why I was so fascinated with Krulwich’s revisionist theory.
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One theory I heard attributed the demise of men’s formal hats to Eisenhower’s successor John F. Kennedy. I can’t recall a picture Kennedy wearing a hat while president.
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