What is the difference between continental US contiguous US and lower forty-eight states?

The contiguous U.S.is made from the lower forty-eght states plus the District of Columbia. The continental U.S. contains the contiguous U.S. plus Alaska.

Since the District of Columbia is not a state, when you speak of the lower forty-eight, you are not including D.C.

Remember it this way. Alaska is part of the North America continent, hence it is part of the continental U.S. Generally, you don't say contiguous 48, just contiguous U.S.

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