According to documented history, Lombardi's was the first American pizzeria. Pizza didn't gain its popularity until just after World War II, but Lombardi's, opened by Gennaro Lombardi, began selling pizza in New York City in 1905, so you might say Gennaro is the father of American pizza. Lombardi's was originally a grocery store, but it soon became a popular stop for workers looking for something to take to work for lunch. Gennaro started selling tomato pies, which were wrapped in paper and tied with a string, and the many workers of Italian descent would take them to the job site. Most could not afford the entire pie, so it was often sold by the piece. There was no set price or size, so you asked for whatever lets say 2 cents would buy and you were given portion of what was equal to the amount offered. Gennaro's son, John, took over after Gennaro passed away and the business eventually went to Genarro's grandson, Jerry. Over the years, Lombardi's continued to sell pizza, becoming a cult-like Mecca for pizza enthusiasts. In 1984, Lombardi's closed its doors. In 1994, John Brescio, who was a childhood friend of Gennaro's grandson, Jerry, started talking to Jerry about reopening Lombardi's and in that same year they did, but not in the same location. They moved a block down the street to 32 Spring Street.
For more details on Little Italy, see this picture.