Why button-down shirts?

[hksj]

I'm at a loss as to why button-down shirts exist and are considered more casual. Did this perhaps make more sense when collars were expected to be kept more rigid? Could anyone explain? Thanks.

 

[Tomasso]

Button down collar shirts originated when Polo players had their collar points buttoned down to keep them from flapping in the wind when they played. Therefore, they are the first sport shirt and have always been thought of as being a bit casual. That said, they are worn for dress in the U.S. and many other countries, especially Italy.

 

[scotrace]

They keep collar points from making flippy-flop in a wind.

 

[Harp]

I prefer 'em for crew neck sweaters.