Gennaro Lombardi was a Neapolitan immigrant to the United States, arriving sometime in 1895. He settled in the densely-packed neighborhood on the Lower East Side known then and now as Little Italy, and in 1897, got a job as a clerk and stock boy in a local grocery.
Fortunately for Signor Lombardi, he had been a baker in the Old Country, and decided to begin baking pizzas as a sideline to his boss' grocery business. For lack of cash, he was forced to use the store's coal-fired stove for his baking, and a similar lack of cash forced him to substitute fior di latte for mozzarella di bufala in his pizzas. It didn't matter. Business boomed as word spread that pizza had appeared in America.
The friendly rivalry between the two men presaged the "Pizza Wars" of the early 20th Century, as other pizzaiolos, coming late to the table, vied to give customers "The Best Pizza in New York"---and thus, America.
Sorry, Chicago. Don't even think about it.