Anytime I see paintings of prominent Americans from the late 18th to early 19th century (i.e. Presidents), they are clean shaven. If you think of the Founding Fathers, there’s nary a whisker among them.
But, by the middle of the 19th century, it seemed that any male who could grew some sort of facial hair. Why the change?
In our modern times, it seems that popular culture gives each decade a unique “look”. I attribute that to the influence of various media influences (i.e. Farrah Fawcett’s feathered hair in the 70s, or Madonna’s Desperately Seeking Susan look in the 80s). I assume, then, that there was some sort of “pop culture” influence that accounts for the ubiquotous mustache of the mid to late 19th century (clearly, before the invention of mass media like the TV or radio, trends changed more slowly then they do now). But I’m at a loss as to who, or what, created the change in normal male appearances.