If you live in a metropolis for long enough, you might just be used to rotating doors. It’s more noticeable if you are visiting from smaller towns. 

New York and Chicago are the two biggest markets in the United States for revolving doors, or “revolvers”. 

The first revolver was installed at Rector’s in Time Square in the late 1890’s. People were hesitant to try the new contraption with the concern that limbs would get stuck. 

The revolving door, then “storm-door structure” was first patented by Theophilus Van Kannel of Philadelphia on August 7, 1888 as a noiseless way to prevent the entrance of wind, snow, rain,  or dust. Kannel also values the door’s ability to have one continuous motion of people in and out of a building. 

Revolvers are beneficial for tall buildings in cold climates (Chicago and New York both apply). Warm air is less dense and rises to the top through the elevators shafts. Known as the stack effect, it creates suction because of the warm air in the building and the cold air on the outside (especially with Chicago winters arrive). This is resolved through the release of air through the use of revolving doors. 

They are also energy efficient, retaining heat by acting as a drift block. The drift block is also beneficial for restaurants so tables near the doors are comfortable by temperature and blocking out noise. 

Retail stores also benefit from revolving doors, as they keep the wind from blowing shit over.

Sources: Curious City / La Crosse Tribune / New York Times / Mental Floss