Sometimes it is possible to get cheaper solutions by having a look at limited offers or at fidelity programs made available on the companies' websites.
When travelling on such short distances, you can take into account also busses and carpooling options: with some luck you will find very cheap options, even if you book on short notice.
What are the departure and arrival stations in Washington, DC and Baltimore, MD?
Trains leave Washington, DC from Washington, DC and arrive at BWI Airport, MD or Baltimore, MD.
How many train connections exist to go from Washington, DC to Baltimore, MD per day?
How long will it take you from Washington, DC to Baltimore, MD by train and when do the trains leave?
On average, it takes 28 minutes to get to Baltimore, MD by train, but you will need 23 minutes with the fastest trains. The first one is available at 03:09, whereas the last one leaves Washington, DC at 21:09.