This ad for a sack suit is in the New York Public Library’s Digital Gallery, and is dated 1900. Click on the picture to enlarge it. The model is drawn to be svelte, but the jacket is still big. On an ordinary man, the jacket was big and boxy.
The caption reads, “The New Bowdoin Sack Suit” and below it, “About the nobbiest that you will see this season.”
I love the style of the text — the voice — in ads around 1900. They all sound as if they were written by the same person.
Sack suits were more casual than knee-length suit jackets, called frock coats or frock suits, which were formal but still for daytime.
“The sack suit … was leisure wear for men who might wear a frock coat, and the best clothes of vast majority of American men,” writes Walter Nelson. “A banker would wear a sack suit to a picnic, and a cowboy or farmer would wear it to church,” he writes at The Gentleman’s Page , an entertaining resource about historic menswear on http://WalterNelson.com.