Many elements of newspaper production in the early twentieth century are similar to the way they are today. Editors assign stories to their reporters or the reporters gather content concerning their respective beats, such as political, business, sports, and so on. Once reporters submit their initial stories, the process goes through a series of revisions and editions until it is fit to print.
I assume, however, that you are asking about the printing process itself. That has indeed changed significantly since 1931. Back then, most newspapers were printed using a linotype machine. These were large machines that got their name because they printed an entire line of type at a time. Using a complex mechanical keyboard, the print setter arranged each line of type. Once this was assembled on a print block, lithographic images were added to the plate as needed. It would then be inked and large long reams of newspaper would be run over it on mechanical belts. Then the papers were mechanically folded, arranged in order, and sent to distribution centers to be delivered. This method was used into the 1970s. You can check out this video to see what the operation looked like in practice.
This was a complicated process that required many steps to function. However, the operation was streamlined to the point that a well-run publication could print each copy in a matter of seconds.