Usui Pass - Usui Pass

A pass that forms the border between the Matsuida-machi area of ​​Annaka City, Gunma Prefecture and Karuizawa Town, Kitasaku County, Nagano Prefecture. There are old and new passes, and the old Usui Pass was praised as the most rugged natural hazard on the Nakasendo Road, along with the Hakone Pass on the Tokaido Road. It is recorded as Usuhi-no-saka in the Nihon Shoki and as Usui-zaka in the Manyoshu, and has been an important pass connecting the Kanto Plain and the Central Highlands since those days. Sakamoto on the eastern foot of the mountain is 502 meters above sea level, so the pass is reached after a climb of 8 kilometers, or about 450 meters above sea level, and the west of the pass is a flat plateau. There are old and new Nakasendo roads. The old road went around the north from Yokokawa and Sakamoto, and connected the Togemachi area to old Karuizawa. Yokokawa had Usui Barrier, which was protected by the Annaka Domain, and Sakamoto had a post station. The new road was built to the south of it in 1883 (Meiji 16). In 1893, the Shinetsu Main Line was opened to the north of the new road. Due to the steep gradient of 66.7‰ (per mille) for the 11.2 km section between Yokokawa and Karuizawa, it used the Abt system track, which is rare in Japan. However, this was abolished in 1963 (Showa 38), and a normal system track was laid. Later, with the opening of the Nagano Shinkansen in 1997 (Heisei 9), the Yokokawa-Karuizawa section of the Shinetsu Main Line was abolished and transportation was switched to buses. The new road is National Route 18, and is fully paved, but because it has many curves and heavy traffic, the Usui Bypass Road was opened to the south in 1971. The pass is beautiful with both fresh greenery and autumn leaves, and the old road is good for hiking, with many visitors to the remains of the Usui Checkpoint and Kumano Shrine in Toge Town. In addition, the tunnels, bridges, old stations, and other facilities of the Usui Pass railway have been designated as Important Cultural Properties by the national government.

[Murakami Sadao]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

群馬県安中市(あんなかし)松井田町(まついだまち)地区と長野県北佐久(きたさく)郡軽井沢町(かるいざわまち)との境界をなす峠。新旧の峠があり、旧碓氷峠は、中山道(なかせんどう)第一の天険として、東海道の箱根峠と並び称せられた。『日本書紀』に碓日坂(うすひのさか)、『万葉集』に「宇須比」坂と記載されて、当時から関東平野と中央高地をつなぐ重要な峠であった。東麓(とうろく)の坂本は標高502メートルなので、比高約450メートルを、8キロメートル登って峠となり、峠の西は平坦(へいたん)な高原となる。中山道には新旧があり、旧道は横川(よこかわ)、坂本から北方を回り、峠町(とうげまち)地区から旧軽井沢に通じた道路で、横川に安中藩が守った碓氷関、坂本に宿駅が置かれた。新道は1883年（明治16）その南方につくられた道路で、1893年新道の北に信越本線が開通し、横川―軽井沢間11.2キロメートルが66.7‰（パーミル）の急勾配(こうばい)のため、わが国では珍しいアプト式軌道によった。しかし、これは1963年（昭和38）に廃止となり、普通方式の軌道が敷設された。その後、1997年（平成9）の長野新幹線開業に伴い、信越本線の横川―軽井沢間は廃止、バス輸送に転換された。新道は国道18号となり、完全舗装の道路であるが、カーブが多く、自動車の交通量がきわめて多いので、1971年その南方に碓氷バイパス道路が開通した。峠は新緑、紅葉ともに美しく、旧道はハイキングによく、碓氷関所跡や峠町の熊野神社を訪れる者も多い。また、碓氷峠鉄道施設のうち、トンネルや橋、旧駅などが国の重要文化財に指定されている。

［村木定雄］

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