TexasCHLforum.com

With a Texas CHL, you are legal to carry in all the states along your route until you reach DC. If I were you, I would get a hotel or stay with a friend in Virginia--you can't carry in Maryland, and staying in Virginia saves a couple of hours on the end of what is a very long drive. Take the Metro into DC each day and leave your gun locked in your hotel room or car.

As for what you should look out for while carrying along the way, a few more specifics would be helpful (are you planning on driving directly to DC or sightseeing along the way; where are you planning on stopping), Alternatively, take a look at the laws on http://www.handgunlaw.us or http://www.packing.org.