When North America was first settled, pioneers built their homes of logs. To aid in falling the timber, they made U or V-shaped cuts at the tree's base. Similar cuts were made in the logs to hold their cabins together. They called these cuts NOTCHES.
As the settlers moved inland from the coast, they discovered in the mountains, openings, or narrow passages, shaped like the notches in the logs of their cabins.
Since those early days, the term NOTCH has been used here in New Hampshire where first trails, then roads, passed through narrow openings in the mountains.