It's possible to do approximately 11 miles out and back from Jerusalem Mills going north on the White Trail. Yesterday, however, it wasn't possible to cross the stream because the water was so high, so limited to about 4 miles.
The longest trail is not well trekked and goes about seven miles one way to Harford County. The longest circular path is about 5.5 miles. You have to string together three trails to do the complete loop.
Thanks! Your answer is awaiting moderation.