The Sack Suit
The sack suit, walking suit or business suit (or, in Britain, the "lounge suit") was leisure wear for men who might wear a frock coat, and the best clothes of vast majority of American men. A banker would wear a sack suit to a picnic, and a cowboy or farmer would wear it to church.
It first came into fashion in the 1850s as a very large, baggy garment, and then became more fitted during the '60s. It evolved into the modern three piece suit.
Its popularity was assured by the fact that it could be purchased, ready made, at prices working men could afford
To the left is a summer sack suit, of white linen or lightweight wool, with a straw hat. Linen sack suits tended to be baggier than wool ones. Click on the image to see a larger view.
Note that one often sees straw hats worn with dark, winter weight wool suits as well, as the 19th Century gentleman's only concession to summer heat.
The most common colors were black or gray, and the pieces usually, but not always, matched. They could be almost any color though, and plaid was particularly popular.
The coat usually had four buttons, the top one of which was generally buttoned--the rest left undone.
The gentleman on the right is breaking the rule of matching trousers and upper garments, and is in fact wearing the striped gray tousers which one is supposed to wear with a morning or frock suit. Since he is also wearing a white tie, he may be a member of a wedding party, and this is his way of "dressing up" his ordinary sack suit, or maybe he is a just an American and doesn't worry too much about "the rules".
Note the splendid tall crowned bowler hat (typical of the late '70s and 1880s), the watch chain attached to one of the top vest buttons, the vest cut straight across the waist, and the bone, wood or gutta-percha (gavinized rubber) buttons. On frock or morning coats, the buttons were usually covered in silk or other fabric, while they were usually uncovered on sack suits.
The sack suit permitted any number of hat styles. When it was a new idea, in the 1850s and '60s, it was often worn with a top hat - but by the 1870s, top hats were limited to frock suits, morning suits and evening wear, and sack suits were worn with bowler hats and pretty much every other sort of hat a 19th Century man could find.
Click on the image for a larger view.