One thing to keep in mind regarding Metro is that last year on the 4th Metro changed the color system and destinations of some of the train lines to make it somewhat more efficient. As a local it was kind of odd to see how they switched some of the subway lines and colors from what they normally are! Be sure to look for the actual station when you arrive at DCA and not just the color of the subway line in case they have made this change again this year. If they do this again it will only be in effect for July 4th...it will go back to the regular map after the holiday.