Is ther a city that would be capitol if Washington D.C. gets captured?

The city of Atlanta, Georgia, has been designated as the backup capital of the United States in the event that the capital city of Washington, D.C., is ever incapacitated. The selection of Atlanta as the backup capital was made by the United States Congress in 2004. It was chosen due to its strategic location, its infrastructure, and its relatively large population. Atlanta has also served as the temporary capital of the United States on a number of occasions throughout its history.