Wow I had no idea Americans used to drink more coffee than now. Surely serving sizes have grown and grown - absolutely nobody was having a 20-ounce coffee in 1946, but now that's normal. Doesn't seem to add up but I'm sure you're right.
Perhaps the US used to drink espressos in the 1940s, I'm not sure. That's if this fact is even accurate.
US consumption in 1946 was apparently ~20 pounds of coffee beans annually per capita, or an average of around 2.5–3 (8 oz?) cups of coffee per day for the ~3/4 of adults who were regular coffee drinkers.
Per https://www.retrowow.co.uk/food_and_drink/coffee/coffee.html
> Most people [in the UK] made coffee in a jug. You boiled the water and added it to ground coffee already in the jug. You let the ground coffee settle and it was ready to pour through a strainer and drink. Some people then boiled the coffee again.
My impression is that coffee preparation was comparable in the USA. Neither paper filters nor instant coffee were common until decades later.
Espresso was unknown in America back then. Rumor has it that GIs, when exposed to it, diluted it with hot water, giving us the modern Americano. [0]