When and Why Did Pizza Take Off in the U.S.?

I did a post the other day about Veltre's, a defunct bakery that sold bread and pizza from the 1930s up to about 2000. That got me thinking about the conventional wisdom holding that pizza took off in this country in the late 1940s, as soldiers returning from Italy wanted the "pizza pies" they'd developed a taste for overseas. Typical is the statement I found on this website that "The post-WWII years exposed millions of American GI's to pizza in Italy."
Now beyond the fact that it doesn't make any sense to say that the post-WWII years exposed American soldiers to pizza in Italy, I have some doubts about that, for a few reasons, but first let me mention two things that came out in my conversations with the Veltres.
Angelo stated that pizza sales began increasing in the early 1940s. Now we're talking about things that happened, gradually, some 70 years ago, so his memory might be off by a few years, but I think in the case of Veltre's, he's probably about right. Veltre's was selling "tomato pies" in the 1930s, and they began to catch on in a relatively short time, thanks to walk-in traffic from customers coming to buy bread, and from sales to the patrons of nearby bars on Lyell Avenue.
There's also evidence, corroborated by Dave Veltre, that pizza in general changed later than the 1940s, and - not coincidentally - that those changes were accompanied by a more dramatic increase in pizza sales. The 1950s and '60s were when "modern" American pizza evolved and became standardized. Part of that was due to marketers spreading the word among pizzeria and bakery owners that if they wanted to keep up with the times, they had to switch to low-moisture, processed mozzarella, and offer various toppings, especially sliced pepperoni. The 1960s also saw the birth of national pizza chains like Pizza Hut and Domino's, although it would take some years for them to achieve national prominence.
There's also this article from the Wall Street Journal showing that pizzerias were barely a blip on the radar screen in our nation's pizza capital as late as 1958, and that the real quantum leap came over the next two decades.
None of this supports the theory that WWII vets were what drove the growth of pizza sales, either in Rochester or in the U.S. generally. First, if Angelo Veltre is correct that sales were increasing in the early 1940s, that wasn't from returning soldiers. We invaded Sicily and mainland Italy in June and September 1943, respectively. Not many soldiers would've been returning from Italy before 1944, with most returning beginning in mid-1945, after the war was over. The total number of troops sent to Italy, though large, was still relatively low as a percentage of all U.S. military deployments, and certainly not in the millions. And even among soldiers who were sent to Italy (who probably got far more meals out of a can, or in a mess tent, than in a ristorante), many, maybe most, would not have run across pizza, which was still very much a purely regional dish in Italy at that time. The WSJ article quotes one NYC pizzeria owner as stating that during his great-grandmother’s day, “in certain regions of Italy they didn’t know what pizza was.” And I recall a WWII vet who served in Italy telling me that he never ran across pizza during his time there, and that he never heard of pizza until years later, in this country. So if pizza sales were increasing in the 1940s, it was probably more from word of mouth among customers of Italian-American bakeries.
The explosion of pizza sales later, in the 1950s and '60s, is probably attributable to several factors. Again, the Journal article notes that it was in the late 1950s that affordable gas pizza ovens became widely available, obviating the need for wood- or coal-fired ovens, and making it a lot easier to bake pizza on a commercial scale.
Beyond that, the '50s and '60s witnessed a broader transformation of American eating habits, particularly the birth of fast food, fueled by the rise of mass media and advertising, a consumerist culture that emphasized convenience, and an emerging new youth culture. It's no accident that burger chains started growing at around that same time.
So - did veterans returning from Italy give rise to pizza's popularity in the U.S.? I doubt it. Some G.I.s no doubt developed a taste for Italian food, but that would hardly explain pizza's phenomenal rise in popularity from the late 1950s on. No, I think pizza took off because it got easier to make, and because Americans realized that it's just flat-out good.