Were you the one who flew by me the other day on the highway. I was cruising about 75.
Google maps shows the distance between National Harbor (Maryland route) and the Capital building as 17.5 miles by the way.
You and google must have gotten lost somewhere in the city! Did you take the beltway all the way to pennsylvania ave and than follow it in, lol? Or maybe you forgot and crossed the Wilson Bridge into Alexandria?
Check it again - it's less than 10 miles - use 295 and the southeast freeway. It's the most direct route.
There is also a shorter, distance route. But it's all lights and takes you by Bolling - will take much longer in minutes.
As for the 75 miles an hour comment - anyone choosing to drive, please be aware that DC uses a mobile camera system on 295 and will ticket you just enough so you end up paying versus fighting it.
And - another geography lesson - everything inside the beltway is not DC.
Maryland and Virginia have substantial communities inside the Beltway.
National Harbor is in Maryland. It is on the Potomac River just south of the Wilson Bridge and is outside the beltway by maybe a quarter of a mile - want to make this clear so some don't take previous comments to mean off miles into suburbia. As you cross the bridge for those driving back from Disney or other Southern areas, take the 'local' route (it won't cost you any extra time) and look to your right. It is the sprawling complex on the side of the hill, extending down to the river, with several piers and a couple of permanent white tent type pavilions.
You can follow the signs and drive in and check it out very easily, or maybe have dinner there. There are quite a few dining choices, some moderate and some quite pricey such as Old Hickory at Gaylord. It exits right from the beltway 95/495 - it has it's own exit marked 'National Harbor" and you can go right back onto the beltway. Easy peasy!!!! National Harbor has a website to give you info on what is there.