Sorry I'm not able to help with that information.
It's quite a walk depending on traffic and your sense of direction
Travel by car sorry
You will have to reach Union Station first with the train, then take the metro to Metro Center, and then to Federal Triangle. You go through the Ronald Reagan Building and the museum is across the street. On a nice day, you could walk from Union Station but it would be a hike!
About a 20 minute walk from Union Station.
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