A megalopolis is a continuous amalgamation of a series of cities. It refers to a large urbanized region that comprises several cities or metropolitan areas, which are closely situated and physically linked together. The individual cities in a megalopolis tend to grow and merge with each other over time, resulting in a vast, interconnected urban area with a very high population density. The term is often used to describe areas such as the Northeast megalopolis in the United States, which includes cities like New York, Boston, and Philadelphia, among others.