Anything west of Frederick and/or South Mt has always been western Maryland. Always.
Frederick has been the canonical answer for half a century. But 270 is bringing MoCo north and northwest.
Hagerstown is just far enough out that it would be a very formidable commute to DC. I don’t have a sense of how many people may do that. I’ve known people who commuted from Winchester and Harrisburg (just one, to be fair), so I assume there must be a few.
For all its faults, Montgomery County is still holding the line on development through its “Agricultural Reserve” in western MoCo. Preservation and anti-sprawl groups are also still blocking another Potomac River bridge, which the Fairfax and Rockville carheads desperately want.
As you know, the world here is divided between people who think DC is too big already vs. those who there’s money to be made in feeding the cancer.