Agree with other posters that public transport may actually be almost as fast as a cab or Uber, and far, far cheaper at that hour of the day on a weekday. Washington Flyer to Wiehle Metro stop leaves every 15 minutes and is $5, then the Metro fare to DCA will be an additional $5.90. Assuming you have only one substantial piece of luggage and it's on wheels, no problem. More than one would be awkward however.