Why do Americans wear tuxedos to symbolize a formal event, or for that matter coats and ties for official dress up events. These are interesting questions and the answer may surprise you..

The tuxedo evolved from military uniforms of the 19th century. The uniforms of the day had long tails and were worn with the sashes of the various regiments. This evolved into the civilian full dress suit (tails) and the more familiar suit length tuxedo jacket, which is still worn with a cummerbund reminiscent of the regimental sashe

 

http://www.thingstolearn.net/2012/05/why-do-men-wear-neckties/

https://en.wikipedia.org/wiki/Formal_wear

http://www.blacktieguide.com/White_Tie/White_Tie_Tailcoat.htm

http://www.wsj.com/articles/SB10001424052748704132204576285250103874450

The Origin of Tuxedo – Who Invented Men’s Formal Wear