In New York Night: The Mystique and Its History, author Mark Caldwell writes about the post-Pearl Harbor dimouts in New York City. The week following December 7th, 1941, involved the governor, Herbert Lehman, and Mayor La Guardia instituting practice blackouts and drills as precaution against air raids. Eventually, however, defense officials realized that New York's signs, streetlamps, residential lights were the biggest threat... which led to the dimouts.

"Dimouts were the best and most easily achieved defense: New York's began on May 18, 1942, and lasted until 1945. All illuminated advertising had to be shut off permanently. Theaters were allowed faint outside lights, but only on the undersides of their marquees to guide patrons leaving and entering. At home any lamp visible outdoors had to beam downward. Anyone living above the fifteenth floor of as skyscraper with lights visible from the sea had to douse them or hid them behind black out curtains.
In Times Square the effect was drastic. The Swimming fish in the Wrigley sign, the peanuts that endlessly tumbled from a Planters bag, and the glowing Sunkist sunburst all froze into stillness and went dark. The Times tower news ribbon clattered to a halt. The Camel billboard... its handsome smoker, now unlit, nevertheless still puffed out his five foot smoke rings which floated out over a darkened Times Square."

Poetic! Click through from photos of that time, all of these were taken in 1942 and 1943.