In movies of the thirties and forties, a stock character was the poor shmoe from the wrong side of the tracks whose parents couldn't afford to send him to a good college, so he had to go to "State." An additional twist of the knife in this poor sod's guts was that he had to spend his summers working at a soda fountain or something in order to pay for school.
Was it really possible to work for the summer back in the twenties, thirties and forties and save enough money for an entire year of tuition, books, food, and so on, or was that just a movie thing?
If the summer job was a high paying one, yes it was. Soda jerks were not paid very well, so that is not realistic. However, here are two examples of future railroad presidents, that worked their way through college by having a summer job. Alfred Perlman worked as a surveyor for the Northern Pacific railroad. John Barringer worked as a bank teller. Barringer got into the railroad industry, after starting out in the Reconstruction Finance Corporation, during the Great Depression.
State Universities were much less expensive back then.
Sources: For Barringer. "America's most noteworthy railroaders" Railroad History # 154 Spring 1986.
"Perlman the Magnificent: Alfred E Perlman, Czar of the New York Central, Savior of the Western Pacific. A star wherever he went" by H J Bruce. Trains Magazine. March 2002