FORTUNE — Reading dusty old magazines can offer a powerful glimpse back in time. You get a sense of how people thought at a specific point in history, unfiltered by hindsight. You see how the daily lives of people have changed, and in case you needed evidence of how much the world of work has changed over the last half century, a read through Fortune’s 1956 take on the college senior hiring scene is an intriguing start.

As Fortune’s Herrymon Maurer put it, “This month of March, 1956, will be the most hectic month in the biggest year of college-senior hiring in U.S. business history.” With the economy booming, and the American corporation growing more complex, higher salaries “demonstrate a rising premium on college men in business…. While promising high-school graduates are carefully sought, it is clear that corporations generally expect to find their future leaders on campuses.”

Yes, of “this year’s crop of over 200,000 men graduates, the great majority of them will eventually go into business.” (According to government figures, women earned 132,000 of the 379,600 bachelor’s degrees conferred in 1956, but Fortune didn’t bother to mention them.). “Business is ready to hire them in great numbers,” Maurer reported. Sears, Roebuck SHLD planned to recruit 500 students. General Motors gm “is aiming for 2000 and would take as many as 800 more if it could get the ones it wants. And General Electric ge expects to take on a grand total of 2,500.”

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It sounds very rosy, but Fortune set the tension in the story’s title: “Twenty Minutes to a Career.” The basic contact between companies and students, Maurer wrote, was a 20-minute interview. Students should know that “For a great many of them, a brief interview will settle their careers for life.”

For life? The “estimated three-quarters of the business-minded graduates who will go to work for large corporations” should “consider a job offer in terms of a lifetime career,” Maurer asserted. “To be sure, some large companies will hire men two or three years out of school, and a few will take them even after five years. But almost all of them hold to the policy of promotion from within…. For the bulk of the men who aspire to a big-business career — and for the bulk of the companies hiring them — the year of college graduation is the year of decision.”

Fast-forward a little more than 50 years. The surviving men from the class of 1956 would be well into retirement now, but the odds are good that most did not retire in 1999, at age 65, from those corporations that hired them 43 years prior.

One reason? Many of the companies mentioned in the 1956 article don’t exist in anything approaching their original form. Jones & Laughlin, a steel company, told Fortune it planned to recruit from 35 colleges. In 1984, it merged with Republic Steel to form LTV Steel, a company that filed for bankruptcy in 2000.

American Can was highlighted in the article for its selectivity, interviewing 800 men and hiring 150. By the 1980s, American Can had morphed into a financial services conglomerate that eventually became Primerica PRI .

The two largest railroads, the Pennsylvania and New York Central, were in 1956 “transforming their personnel practices to stimulate the interest of college graduates,” Maurer wrote. By 1968, these two rivals had merged; in 1970, the combined company went bankrupt.

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But beyond the sagas of mergers, acquisitions, and bankruptcies, it soon became clear that companies were not holding to the policy of promoting from within. Changing jobs soon became normal, and people soon sought to do it proactively to move ahead.

Princeton University does informal surveys of alumni approaching major reunions. In 2009, 60% of men from the class of 1964, just a bit younger than Fortune’s men of 1956, reported changing jobs three or more times during their working lives. Only about 12% of the class of 1964 had never changed jobs. Indeed, more than 50% of the class of 1964 reported that they had changed careers.

So perhaps those 20 minutes did not set a life’s course, never to swerve again. But at least some of the wisdom quoted from placement officers is relevant today. As a counselor at the University of Cincinnati put it to the men of 1956, “Weigh everything that the recruiter says and that you read in print; then use what you have learned and judge for yourself.” That’s good advice — especially if any recruiter starts waxing eloquent about careers for life.