Polebridge to Numa Ridge Phoneline - Credit: Wikimedia Commons
The Polebridge to Numa Ridge Phoneline is a historic communications path in Glacier National Park in the U.S. state of Montana. The line was the last remaining single-line crank telephone network in the American West. The remaining line, insulators, and terminals are instructive of early communication technology. The system includes the remains of a single strand system using an earth ground. Wire was strung through ceramic insulators mounted on trees. Phone poles still stand in the meadow south of Kishenehn Ranger Station, and a phone remains in place at Bowman Lake. Read more on Wikipedia
Source: en.wikipedia.org