A lot depended on how far we were going, for how long, and how many people were in the group. The more hikers there were, the greater amount of community stuff you could bring.
For an overnight hike, it didn't much matter. In fact, given the equipment we had, bulk was a bigger consideration than weight per se. The longer the hike, obviously, the greater attention had to be paid to weight and bulk---although sometimes we could plan things so that resupply was possible.
Back in the day we'd usually carry canned/frozen/fresh foods for the first night out. Sure, they were heavy and bulky. But that was a self-correcting problem, as is true with all backpacking foods.
Dried foods were the mainstays. And there was quite a selection. Don't forget that "evaporated" foods date to the 19th century, and reached their nadir with the Yukon gold rush.
Whole grains were an oft-used foodstuff. What we'd do is put it up to soak on the lunch break, and by suppertime it only took a short while to cook. TVP was readily available, too, because it was used to stock bomb shelters.
There were some interesting foodstuffs developed for backpackers. Many of them were based on the idea of pemmican, only updated and modernized. IIRC, Wilson was the big name in such products.
Even supermarket shelves were a source of lightweight foods. Remember, the late '50s and early '60s marked the introduction of the convenience food revolution. So there was plenty to choose from, although the quality sometimes left something to be desired.
Even with the convenience products we would repackage to reduce bulk and weight. No, a cardboard box didn't weigh much. And on an overnight it wouldn't have mattered. But when you're out for ten or 15 days, carrying everything on your back, even fractions of ounces counted. Some people even trimmed the margins off their topo maps to save weight.
Many of us made our own snack foods. It's been said, with some justification, that backpackers don't eat meals. Instead they just munch their way down the trail. I still make many of my own trail foods, and you can find directions for making some of them at
Backpacking Food - Friendly Carbohydrates And, of course, GORP remains a mainstay today.
The big problem for long distance packers, particularly up high, is that you loose your taste for fats. So it was important to find a way to make fats and oils palatable---one reason GORP was important. Everybody, in those days, carried tropical chocolate bars. And nobody that I know ever ate one.
In the mid-sixties things took a turn for the better. MRE and spacefood technology was quickly transferred to the retail market, as did freeze drying. So there was, on one hand, a burgeoning selection of food in the specialty shops (at least three major companies offered freeze-dried selections), and, on the other, the same influences in the supermarket. Nowadays I would probably stock up for a long hike completely in the supermarket. Or 90% at any rate.
For instance, a can of tuna in oil or water is not something you'd carry past the first day or two. But those modern foil pouches weigh barely more than a similar sized package of freeze-dried whatever. And the sharp flavor of the tuna often provides a lift when you're getting pretty tired of freeze dried and carbs.