Summary: The USA will get a new capital city, among other new things, and Washington, DC will be abandoned as the capital.
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Admin Note: While there's no prophecies saying specifically where this new capital may be, several have mentioned that there's a backup White House in the Ozarks, in Michigan, in Colorado, in Florida, and a few other places. Also, I don't read this as the city being completely abandoned. It'll just cease to be our capital, but will remain inhabited.