In the United States, it was not until the late 18th century that establishments that provided meals without also providing lodging began to appear in major metropolitan areas in the form of coffee and oyster houses. The actual term "restaurant" did not enter into the common parlance until the following century. Prior to being referred to as "restaurants" these eating establishments assumed regional names such as "eating house" in New York City, "restorator" in Boston, or "victualing house" in other areas. Restaurants were typically located in populous urban areas during the 19th century and grew both in number and sophistication in the mid-century due to a more affluent middle class and to suburbanization. The highest concentration of these restaurants were in the West, followed by industrial cities on the Eastern Seaboard.