One of my favorite Union Suit articles was written by Bill Reed, dated December 6, 2005, and was entitled: State of the Union Suit!   Hopefully, he won't mind a partial reprint.  

It began: 

"Maybe it's the sheath of cotton running seamlessly over the body like a second skin. Maybe it's nostalgia. Maybe it's the giggle-inducing flap that buttons up in back. Or maybe, just maybe, it's an elaborate excuse for men to pull off those tighty-whities and slip into bright-red underwear.

Whatever it is, the venerable union suit won't go away....The one-piece wonder of long underwear has been around for nearly 150 years, and sparks vivid memories for its devotees."

From:     gazette + state-of-the-union-suit