There are a couple of breath-taking trails in MD that I don't think should be overlooked.
The first is the NCRR or North Central Railroad trail. This trail extends from the Loch Raven Reservoir (Northwest Baltimore County, MD) to nine miles North of New Freedom, PA (Approx. 50 miles roundtrip). It is a gentle blend of lush trees, rolling streams and farmland. It is slightly hilly but the hills build gradually. The only downside to this trail is the amount of bike and foot traffic on it during the Summer months!
Directions: From Washington D.C. or Northern VA, Silver Spring and
surrounding MD Take 95N toward Baltimore. Take the exit for 695 West toward Towson.
Go approximately 4 miles to 83 North (Timonium/York). Go to exit 18A--Shawan Road. Get off
on this exit and following the ramp around to the right. At the second light (York Road)
make a right. At the next light (Ashland Road) make a left. Go approximately 1 mile and
the trail head will be on your left. You will see a bike rental "shack" on the
right and directly across on the left you will see a very small yellow trail sign
indicating the beginning of the NCRR. If you blink you will miss it so pay attention.
Don't park too close to the trailhead on the side of the street- you will get a ticket.
Also, see the C & O Canal Trail