Like so much in American life, the standard clothing sizes we use today can be traced back to the Civil War.
If that answer sounds glib, it isn’t meant to be.
The Civil War was the pivotal event in American history, marking a transition to the modern era, and heralding changes that stood until the 1940s.
It even changed the way we buy our clothes.
Antebellum Clothing Sizing
There was a limited variety of mass produced, standardized clothing items, mainly jackets, coats, and undergarments, but even these were only produced in limited quantities.
For the most part, clothing for men was made on an individual basis. The Civil War changed that.