DAT's full name is "Dial a truck". They used to have these large screens in truck stops showing loads and encouraging drivers to call for loads.

So I guess these drivers mostly hung out at truck stops (they still do today), just that most truck stops aren't as clean/nice as before.

Woah!! They're like tube TVs at the airport but with loads on them? This is so interesting! I wonder how they kept them updated/what systems that ran on

Yup exactly! I'm not too sure what the early systems were running on but here's a photo of early DAT load boards - https://www.dat.com/blog/life-before-load-boards

They used telephones & personal/professional connections

If they were using telephones, then there were people operating call-in centers for this pool of owner operators? If this was pre-90s, probably not even cell phones but, pay phones/physical phones? And if personal/professional connections, then there were meetings where owner operators get together? How would they schedule time for all of this, or coordinate it?

I'm having a hard time picturing either of these methods. It feels hard to have a large spot market of owner operators without some large broker in the middle, at least pre-cellphones.

Yes that’s correct. If you were owner operator you might be aligned with a particular firm (their name on your truck) and their dispatch would find you loads or you would also know people. You could have a dry van and look for generic loads but lots of guys I knew had specialised equipment (flatbed, tanker, etc) and over time you locked in good lanes and repeat customers. I met a tanker driver once who started in Florida, took orange juice to Canada, picked up some food ingredient in Canada , drove it to somewhere in Tennessee then took something from there to Florida. And repeat. He did that triangle for 10 years. Shipping used to be a real people business. If you had an unusual or unexpected load you’d call your 5-10 providers and they might have capacity or not, or do you a favour and call their buddies for you or not. That would almost always work out, if it didn’t you’d call the sales person from the new 3pl or trucking company who had been wanting your business and he/she would move mountains to get that chance. Definitely an interesting industry full of problems to solve. Don’t think it’s the same any more.

Wow! So really just a large mesh network of phone communication then, and you could make some real money _just_ by scraping together a steady, repeating, geographically connected schedule.

Sounds a lot more human too. Interesting!