They used what were called Linotype machines, which were automated typesetting machines that would cast whole lines of type at once. I kind of love these things, because they were huge, noisy, ubiquitous, and have almost completely disappeared from the modern world. There are very few left, and even fewer that work.
A typesetter would press keys on a keyboard (laid out in order of letter frequency, the so-called “ETAOIN SHRDLU” layout) that would release a little mold from their holders on top of the machine. They would slide down and form the letters of the line of type.
To make sure every mold was column-length, the space between words was marked with “spacebands,” which were long and shaped like wedges. Here’s what a line of molds and spacebands looked like. Before casting the line of type, the Linotype operator would cause the machine to press all the spacebands down at the same time so that the words would expand to fill the line.
Then a molten lead alloy would be used to cast a complete line of the newspaper column (hence “Linotype” from “line o’ type”) from the molds. After it solidified, it would be ejected by the lineotype machine, ready to be used to print and then melted down again to make another line of type.
After a line was done being cast, the molds and space bands would be sent back onto the top of the machine, which would automatically sort them back into the proper racks to be used again.
When the operator was done and the line was cast, he would send bundles off, in order, to the typesetters who could easily slot them in columns in the presses to lay out the finished article.
I worked for a company that replaced linotype machines in newspapers (and publishers/printers) with computers.
Originally, the story was written on a typewriter and then handed to a linotype guy who would then use his keyboard to make the words and spaces that turned into “lines” made of lead.
Someone would then put together these letters/words/spaces in a form that represented the newspaper page. This would then go to the printing presses.
The running joke was that you could always tell a linotype operator because all of his pants would have holes burned in them from the molten lead that splashed.
Eventually, linotypes were replaced with electronic typesetting where a “photo” image of the page would be made and then printed.
The next step was to install computers in the newsroom to replace typewriters and these computers were hooked up to the typesetters.
So… how could a newspaper be printed every day? Easy. These guys were GOOD. And FAST. They knew just what they were doing and could make things happen quickly. It was totally amazing to me to see a guy put together a page of a newspaper with chunks of lead that were actually a mirror image. A fantastic skill that, of course, went the way of the dinosaur.
After the newspaper was printed, the lead “pages” were cleaned and then melted and re-used.
Once electronic typesetting machines were installed, everyone tried to figure out what to do with linotype machines. They were history, of course, but also tremendously big and amazingly heavy. My teen-age son actually wanted one but since we didn’t live in a warehouse – lol – it was kind of impossible.
You can see one in the Smithsonian.
I did this routinely throughout the 1980s. A typical cycle went like this:
3 PM: I type my article and hand it off to someone called a typesetter. She re-enters the story into a linotype machine, which automatically outputs a fully justified column-width strip of typeset copy (called a galley) usually on heavy photo paper.
5 PM: I then take that galley, trim off the excess paper, spread hot wax on one side, and paste it onto a larger sheet (usually called a board or a mechanical). We then physically arrange the different articles, headlines, photos, captions, and ads onto the page. This process is called pasteup. (Sidenote: We used wax rather than glue because you want to be able to peel things off and stick them in different places as you arrange the layout.)
9 PM: The print shop then takes what is basically a photograph of the laid-out page. The negative of that photograph was etched onto a metal plate, which would then be rolled onto a drum in what is called an offset press. The drum is continuously rolled in a vat of ink, then the image is transferred onto a rubber roller, which then prints onto the paper.
Midnight: The presses work overnight to print, trim, and collate the printed pages. Bear in mind that if you’re printing more than one color, there need to be a series of different plates (usually four) to print the additional colors.
4 AM: Trucks collect the finished papers and distribute them to various points for newsstand sales or delivery.
6 AM: The paper hits your doorstep.