Usui Pass
The Miyauchi to Nagaoka section was electrified in 1947 at 1,500 V DC in conjunction with the electrification of the Joetsu Line, with the Nagaoka to Niigata section electrified in 1962, the same year the Takasaki to Yokokawa section was commissioned to facilitate the extension to Nagano the following year via the new adhesion line through the Usui Pass mentioned above. The Nagano to Naoetsu section was electrified in 1966, and extended to Miyauchi in 1969.