D.C. Union Station layout
 

My Amtrak train arrives @ Union Station just 15 minutes before my MARC to Baltimore leaves. Although there is a later MARC I can take, I don't want to wait for it, since this will be late at night. Will I have time to get from the Amtrak to the MARC(I already have the MARC tickets)? Does anyone know where I can find a map of the layout of Union Station D.C., or can anyone explain it?
Thanks so much!!

Assuming your Amtrak train arrives on time, yes, you should have enough time to make the MARC train.

I can't find a layout, but will tell you to just follow the crowd into the train station ... as you enter the waiting area, you'll immediatly see mens' restroom on your right, followed by a Sbarro's pizza. All Amtrak train waiting areas will be to your left. I'll give more info later if I can ... gotta leave building right now.

Not sure where the MARC trains board, but basically the trains at Union Station arrive at about 10 gates, which are lettered (Gate A, Gate B, etc.) and there's a ligted message board outside several gates that shows which gate each departing train will leave from. So it depends on whether your train arrives on schedule and how far apart the gates are. But from one end to the other is certainly less than a 15-minute walk. Be ready to bolt when your train pulls in! The conductor staff on your MARC train might have info on which gates you'll be arriving and departing.

Amtrak travel is not as punctual as Air travel. Trains do slow down in certain areas. So if you are looking at your watch and the schedule your trip will be anything but relaxing. Maybe you should have a back up plan just in case. Good Luck.

NOT QUITE RELATED QUESTION: Does anyone know if there are lockers or checked luggage to store a suitcase for half a day? As you probably know, the lockers at airports have been closed since the Arab terrorist attacks of September, 2001.

I mean in Union Station or somewhere else in Washington DC

There are definitely lockers at Union Station. I think they're still open, but you might want to call to be sure.

The lockers in Washington's Union Station are not in service. However, there is a baggage check. It's a room on the right as you go down the hallway towards the MARC trains, all the way to the left as you face the lockers. You must show identification to check bags.

The National Building Museum has some smaller lockers. the following Smithsonian museums have lockers, but bags will be searched and lockers avail only during museum operating hours:

National Museum of African Art (non-lockable open bins)
Arthur M. Sackler Gallery/ Freer Gallery of Art (lockers-charge a refundable fee)
Hirshhorn Museum (lockers/coatroom)

unionstationdc.com