Favored by artists and mathematicians, the drug powered a great deal of innovation in the 20th century.
Someone really needs to write a history of the influence of Benzedrine on American culture. For a period of about twenty years, from the 1930s to the 1950s, a good bit of American artistic and scientific energy was generated by this lively amphetamine, which was originally created by Smith, Kline, and French in 1928 as a nasal and bronchial decongestant. Soon enough people discovered that it had pleasant, useful, and energizing side-effects, which led to its use by all sorts of people who needed to boost their creative energies.
Google's Ngrams shows us how it rocketed into the public consciousness:
And also helps us see when the cute little pills began to be called "bennies":
As Joshua Foer pointed out in a 2005 essay, throughout the mid-century period scientists and mathematicians as well as poets and novelists relied on bennies to give them the strength to go on. Paul Erdős, who is said to have defined a mathematician as "a device for turning coffee into theorems," neglected in that aphorism to mention that he relied heavily on Benzedrine as well. Indeed, he and many others routinely swallowed their bennies with their morning coffee. Foer notes that "In 1979, a friend offered Erdös $500 if he could kick his Benzedrine habit for just a month. Erdös met the challenge, but his productivity plummeted so drastically that he decided to go back on the drug."
The poet W. H. Auden considered it a sign of weak character that he had to rely on artificial stimulants to maintain his workday discipline, but rely on them he did. For many years he started his days with bennies and ended them with alcohol and barbiturates: he called this "the chemical life." He strongly disapproved of hallucinogenic drugs, of which he wrote, "One is inclined to suspect that habitual taking of this type of drug, even if it has no harmful physical effects, would lead to a selfish indifference towards the common world we live in and a withering of love and affection for others." But bennies did not alter one's personality or distort one's perceptions of reality; they were, in that sense at least, morally acceptable.
Of course, bennies had a tendency to ruin the body of the person using them. Auden's death from heart failure at age 66 was, to a considerable extent, a result of his decades of practicing, with the connivance of his doctors, "the chemical life." The great polymath Norbert Wiener, in his autobiographical I Am a Mathematician: The Later Life of a Prodigy, wrote ruefully, "I tried to work against time. More than once I computed all through the night to meet some imaginary deadline which wasn't there. I was not fully aware of the dangers of Benzedrine, and I am afraid I used it to the serious detriment of my health."
Benzedrine wasn't made a prescription drug until 1959, but by then the fad was already in decline, partly because people could see the damage that bennies were inflicting on their users, but perhaps even more because artistic and intellectual styles were changing. The high-speed, high-energy way was being replaced by something slower, cooler. Kerouac's novel On the Road and Miles Davis's record The Birth of the Cool came out in the same year, but the former was a relic of the recent past, the latter the wave of the future.
Norman Mailer's long essay "The White Negro", another landmark work of 1957, documented a white culture drawn increasingly to, and shaped increasingly by, African-American art. Bennies were not, as Mailer saw things, compatible with that shift. Intellectual culture was moving from the way of the (very white) "psychopath" to the (would-be black) "hipster." The signature drug of the psychopath was Benzedrine, which Mailer himself had used throughout the Forties and much of the Fifties. But, he later commented, as he was drawn to the world of Cool, to the black world, to the hipster world, he shifted to the drug appropriate to that style, that speed of life: marijuana.
UPDATE: Via Matt Frost on Twitter, Here's Harry the Hipster Gibson, "Who Put the Benzedrine in Mrs. Murphy's Ovaltine?" (1944)