One more update for those who might be interested. Here are some figures from my newspaper search.
The search for -- Pepperoni Pizza -- where both words needed to be present for a match to occur but they didn't have to be right next to one another returned the following matches--
1900-1940 returned 1 match and it was for pepperoni by the lb. and for pizza -- not pepperoni pizza.
1940-1950 returned 18 matches where only 1 ad that appeared 6 times in 1949 was for pepperoni pizza.
1950-1955 returned 300 matches where most actually were for pepperoni pizza.
1955-1960 returned 1,400 matches.
1960-1965 returned 4,600 matches.
A search for just "Pizza" between 1900 and 1940 only returned 800 matches, and the vast majority of these were not for the food pizza but were matches of people with the last name Pizza. In contrast, a search for "soda fountain" between 1900 and 1940 returned over 150,000 matches.
By the way, I did find a match for pepperoni pizza in my Google books search that was from the 1930s, but in reading the description I found that they weren't talking a pepperoni sausage but were using pepperoni as the plural for red and green bell peppers.
One last thing, by the 1950s there seemed to be 5 main pizza toppings -- plain cheese, pepperoni, anchovies, mushrooms, and sausage. I know there are some places you can still get anchovies, but this topping is nowhere near as popular as it once was. However, in the early 1980s I was in the Army stationed in Georgia, and I ordered a pizza from a local pizza place. I'm originally from California and when we order a pizza in California we use the term "combination" for a pizza with a combination of ingredients. The guy in Georgia had no idea what I was talking about. At this point I think I was starting to get ticked off, and I'm sure I was getting a little condescending trying to explain that I wanted a pizza with the "works", with lots of toppings at a reasonable price, and I was sure they had something like that even if I didn't know the term used in Georgia for this type of pizza. Eventually he did send me a "combination" pizza, and I probably don't have to tell you this, but it is not a good idea to get testy with a person that is preparing your food -- it was loaded with anchovies (and who knows what else). It went in the trash.