Hi there, Ritamarie. I grew up in VA, currently live in MD outside of DC, spend a lot of time in Baltimore, and make fairly frequent trips to Gettysburg, Philly, western MD/WV, and Fayette County, PA. To me, the mid-Atlantic U.S. encompasses pretty much everything from NJ to the bottom of VA, from the eastern shore through WV. Other folks define the area very differently, though, so you're likely to get a variety of answers to this question.
Got any good routes to share for B'more county or southern PA?