Adam Goodheart has a wonderful little essay on how Honest Abe joined a cultural revolution in the America of the 1850s:
By the mid-1850s, talk of a “beard movement” was sweeping the nation. In 1857, an intrepid journalist strolled through Boston’s streets, conducting a statistical survey: of the 543 men he tallied, no fewer than 338 had full, bushy beards, while nearly all the
rest sported lesser facial hair of various sorts. Only four were “men of the old school, smooth shaven, with the exception of slight tufted promontories jutting down from either ear, as if designed as a compromise measure between the good old doctrine and modern radicalism.”
As that remark suggests, antebellum beards bristled with political connotations. American newspapers reported that in Europe, beards were seen as “dangerous” tokens of revolutionary nationalism, claiming that the Austrian and Neapolitan monarchies even went so far as to ban them. In England they were associated with the sudden burst of martial fervor during the Crimean War. When the trend reached America, connotations of radicalism and militarism traveled with it, spanning the Mason-Dixon Line. It was no accident that the timid Northern Democrats who sympathized with slaveholders like President James Buchanan were called “doughfaces.” Meanwhile, the Republicans’ first standard-bearer, John C. Frémont in 1856, had also been the first bearded presidential candidate in American history. (The most famous antebellum beard of all, though, was John Brown’s.)
Lincoln’s beard was only part of what made his physical appearance seem like a break with the presidential past. Compare the Alschuler photograph to Mathew Brady’s portraits of Buchanan and Franklin Pierce, both considered handsome men in their time. Each wears a high white collar with a tightly wrapped neck stock. Lincoln, with Whitmanesque nonchalance, wears his tie loose and his low, soft collar slightly open. The difference looks negligible to modern eyes, but in a 19th-century context, it was like changing out of a business suit and into a polo shirt...
Lincoln’s decision inaugurated what might be called the Bearded Age in the nation’s political history: for the next half century, only one man would be elected president without benefit of facial hair.
It's enchanting to think of Lincoln as a Whitmanesque bohemian, setting new trends of informality and change in American culture. The NYT also has a slideshow of Lincolnian facial hair.