This curious question was asked by one of my clients when designing a shirt. We have lots of options for the style of the back of the shirt. One is a box pleat with a loop. He asked what the purpose was. Seeing as I have never used one myself I assumed it was decorative but vowed to hunt down the answer.
Here it is: These little loops were called Locker Loops. The stories vary as to the origin of these loops but many seem to think it was an East Coast addition that grew out of the sailors influence. These loops make it easier and quicker to hang your shirts. Especially if you are on a boat and most likely using hooks as opposed to hangers.
Another fun bit of information is how school girls used the loops. Called Fruit Loops the goal was to rip them off the shirts of the boys you found cute. Of course some prefer quantity over quality and the goal shifted to simply accumulating more than anyone else.
Have any questions regarding your clothing? Send them our way, we'll do the research for you! Love the loops? Design yourself a custom dress shirt that has all the bells and whistles you're after. Set up an appointment at email@example.com.