I don't want to make people think Im telling them they are dead wrong. I finally got the official letter directly from White Castle headquarter.
Here is word by word (Only exception is my name) from White Castle:
Dear Diehardbiker
Thank you for your recent inquiry to White Castle. We really enjoy hearing from our cravers!
Unfortunately, no, White Castle never had a restaurant in Washington, DC or its environs.
You may be thinking of White Castle's many imitators such as White Tower or Royal Castle.
Thank you and Crave on!
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End of E mail message from White Castle, Corp.
I had to admit, I love history and sometimes I noticed myself that I do mistook something for something else. I am not ready for membership for AARP!
Now, that I got hard answer from White Castle directly. Too bad, wish we could have WC everywhere, guess WC corp does not want expand too fast. It can be a good thing for them.