My Goal: to travel from DCA to Baltimore Union Station
 

What is the best way to travel by Metro from DCA to Baltimore Union Station? I will not be in a hurry so time is not a factor. Thank you in advance.

Get on the Metro at the airport; get on the Yellow Line to Gallery Place; change there to the Red Lind to Union Station; take the train to Baltimore

Aces to Dukey1.

runnerbee08--you've probably already travelled by now, but just wanted to point out 2 things (though I generally agree with Dukey1's response):

1) Union station is in Washington DC. The train stations in Baltimore are Camden and Penn Stations (Penn Station is the main one). So I assume you meant Baltimore Penn station.

2) As you probably realized from Dukey1's response, you can't get from DCA to Baltimore by the Metro. You can take Metro from DCA to DC's Union Station, and from there take a train to Baltimore. On weekdays you can catch either an Amtrak train (which doesn't stop at Camden Station) or the MARC commuter train (cheaper, and stops at both Camden and Penn Stations). MARC trains don't run on weekends.