Maptitude is the best mapping software for business intelligence! The 2017 Maptitude Country Packages include an updated point landmark database that includes thousands of restaurants, including national and regional pizza chains. The map below shows the concentration of pizzerias by county and what the most common chain is in each state. From this map you can see that there is a somewhat higher concentration of pizzerias in the counties of the northern and plains states.
Pizza Hut, with over 6600 restaurants, is the dominant chain in 36 states, followed by Domino's (5000 restaurants) in 8 states and the District of Columbia.
Map: Created with Maptitude Mapping Software by Caliper, June 2017