Everyone knows the style rule that you're not supposed to wear white after Labor Day. But why? The rule’s origins are surprisingly difficult to pin down, writes Laura Fitzpatrick for Time. The most conventional explanation has it as a practical matter: white fabric was cooler than the relatively heavy clothing worn in the first part of the 20th century, before air-conditioning. Big-city fashion editors lived in the cities during the summer in those days and thus wore white to stay cool, a trend that carried into their magazines.
Others point to Labor Day as the dividing line between summertime vacation wear, which would be lighter colors, and workaday urban duds of a darker shade. With only the well-heeled able to afford vacation, the trend was turned into a hard-and-fast rule in the 1950s—when the middle class was expanding—by old-money types looking to ostracize the upwardly mobile. "It (was) insiders trying to keep other people out," says one historian, "and outsiders trying to climb in by proving they know the rules."