Question: What long, steep, narrow mountain range provides a controversial border that splits Maryland into two parts?
Sentence (from "Sideling Hill"): Sideling Hill (also Side Long Hill) is a long, steep, narrow mountain ridge in the Ridge-and-Valley (or Allegheny Mountains) physiographic province of the Appalachian Mountains, located in Washington County in western Maryland and adjacent West Virginia and Pennsylvania, USA.
Relevant evidence: Yes