The main ingredients in New England clam chowder recipes are bacon, clams, onions, garlic, heavy cream, butter, celery, potatoes, bay leaves, black pepper and salt. These ingredients are combined to create a cream-potato based soup that contrasts the salty and subtle flavors of the bacon and the clams.
The history of chowder can be traced back to Europe and France, where a large cooking pot or cauldron, called a "chaudiere," was used to make traditional stews since the 16th century. The thin stew can be traced to Boston, Mystic, Nantucket and New Bedford. The first discovered recipe dates back to 1751, when the Boston Globe published instructions using pork instead of bacon and biscuits instead of cream or milk as the thickening agent.
While traditional New England clam chowder recipes seldom vary past the main ingredients, there are other variations from different areas of the country that use other foodstuffs.
Manhattan clam chowder uses a clear broth and includes tomatoes for flavor and texture; this style of chowder dates back to the 1890s. Rhode Island clam chowder is also based with a clear broth and uses quahogs, a hard clam found regionally in the south of the state. Long Island clam chowder is a combination of New England and Manhattan chowders, using both cream and tomatoes; the stew's name comes from the fact that New York City is in the middle of the two locations.