I have a confession: I have wanted a union suit for years. I used to do CRM Archaeology, and every time I was shivering my butt off in single digit weather (Fahrenheit), I was super jealous of my coworkers who had union suits. Besides, when nature is your powder room, a removable back panel makes a difference!
Union suits were invented around the same time as jeans. Originating from Uttica, New York, the first union suit was patented in 1868. They were initially a ladies undergarment and part of the Victorian dress reform movement that advocated for women to wear more practical, less restricting clothing. Union suits quickly jumped the gender line, becoming popular with American men as well. They caught on in England shortly after 1878, when a German book claiming that only clothing made from animal hair was healthy was published. An Englishman translated and sold the book in his new shop- one that happened to specialize in clothing made exclusively from animal hair.
All this being the case, it would be eminently reasonable for a steampunk adventurer exploring the colder parts of the world to include a union suit as part of his or her adventuring ensemble.
Top: Vintage Duofold Union Suit from Etsy. Only available as shown. Inner layer is cotton, outer layer is wool. (Wool was what people used before Underarmor- it pulls moisture away from your body, making it an excellent bottom layer material for physical activity in cold weather.) $35
Bottom Left:Unisex Rib Henley One-Piece by American Apparel. Sizing is unisex. Comes in Black, Brown, Cranberry, Rose, Grape Juice, Navy, Dark Sea Green, and Forest (shown). This one does not come with a rear opening! 100% cotton. $38
Bottom Right: Midweight Cotton Union Suit by Carhartt. Available in men’s sizes. Only in Red. 100% cotton. $42
(All of these are only available in Red)
Men’s XXL at Wal-mart. Doesn’t state what the fabric is. $18
Indera Men’s Classic Union Suit at Tractor Supply. 100% cotton. Prices and size availability vary by location; my local price was $22
Duofold Midweight Union Suit in Small-2XL. This is the same cotton/wool fabric as above. Most sizes $38