Slate Magazine has a fun read: Has Modern Life Killed the Semicolon? An excerpt:
From the 1850s onward, it’s virtually impossible to find anyone claiming a prevalence of semicolons in writing. We now lived, complained a critic in 1854, in a “fast era” that neglected punctuation; by 1895, the Times took it for granted that “[m]any writers have adopted the plan of punctuating as little as possible.” What these writers intuited had an empirical basis: A 1995 study tallying punctuation in period texts found a stunning drop in semicolon usage between the 18th and 19th centuries, from 68.1 semicolons per thousand words to just 17.7.
Researcher Paul Bruthiaux notes the steepest semicolon drop-off came in the mid-19th centuryâ€”a finding that matches the gap between Poe’s 1848 complaint and that 1865 “rejection.” Technology is a leading suspect in rapid aesthetic shifts, so consider what debuted in the 1850s that might radically change language usage: the telegraph.
The semicolon has spent the last century as a fussbudget mark. Somerset Maugham and George Orwell disdained it; Kurt Vonnegut once informed a Tufts University crowd that “All [semicolons] do is show that you’ve been to college.” New York mayor Fiorello LaGuardia’s favorite put-down for egghead bureaucrats who got in his way was “semicolon boy.”