Once upon a time, city garbage was removed by crews in horse-drawn wagons. Men lifted every bit by hand and if they overfilled the wagon, debris would fly off the top as the wagon proceeded.
The idea of an enclosed trash truck, so things wouldn't fly out at speed, was started in Europe in the 1920s. It's actually kind of amazing it took someone that long to think of that, but anyway. The Americans thought of the waste hauler we're more familiar with today, the external hopper truck.
But the reason these trucks surged in popularity was because of a man named George Roby Dempster.
Dempster was from Knoxville, Tenn. and a businessman who made his mark in construction and road building before the Great Depression wiped him out. With a background in stuff that required heavy machinery, though, Dempster knew how much labor was required in hauling stuff. He saw garbage trucks of the time and the amount of effort needed for men to throw things into the bed of a truck.