The continental Unite States commonly refers to the 48 contiguous states located on the central part of the North American continent, plus the District of Columbia, and so does not include Alaska and Hawaii. Because Alaska is also on the North American continent, the term, if interpreted literally, would also include that state, so the term is sometimes qualified with the explicit inclusion or exclusion of Alaska to resolve any ambiguity. This ambiguity existed long before Alaska became a state in 1959.