http://en.wikipedia.org/wiki/Meatball
America is a melting pot of different cultures, which leads to an interesting approach to food and restaurants, especially in a city like New York, where there are hundred of different cultures all mixed together. What's also interesting in New York is that foods from other countries and cultures get adopted and then taken as their own. Of course this is true in many countries, there something unique about the way New Yorkers adapt food and grow its popularity. This can be seen with all sorts of food, most notably Pizza, but I also noticed that the humble Meatball also gets the New York treatment.
When wandering around New York, I kept finding Meatballs on the menu of many restaurants, and in fact found a restaurant chain dedicated to the humble fare. Many countries have a variant of the meatball, countries like China are made with pork and usually steamed, while Danish meatballs are a mix of pork and beef and are often fried. Many European countries have their own types of meatballs and each lay claim to having the original meatball, but the style of meatball most common in New York closely align with Italian Meatballs.
In the United States, meatballs are most commonly associated with spaghetti, as in spaghetti and meatballs. There was a large number of Italian migrants that entered the country in the early 19th century, who assimilated the humble meatball dish (along with Pizza) into what is now known as Italian American cuisine. I managed to get to a few restaurants in New York where Spaghetti and Meatballs were the focus and found that while there were similarities in the dishes, there were some very different approaches to this almost ubiquitous food.