Highway - Kaido

An official road or a major land route that runs through the country. It is also written as Kaido. Regarding the origin of the highways, it is said that the Sanyo Road, Tokaido, and Nankaido were opened in Yamato after the establishment of the Yamato Imperial Court, but the Nihon Shoki records that during the reign of Emperor Sujin, four generals were dispatched to Hokuriku, Tokai, Saido, and Tamba, and the Kojiki also has an article that states that they were dispatched to Koshiji, the Twelve Eastern Roads, and Tamba Province. In this regard, the Kojikiden (Motoori Norinaga) refers to the Saido as the Sanyo Road, and does not extend to the Saikaido, and also refers to the Koshido as Koshinokuni, the Twelve Eastern Roads as the Twelve Eastern Provinces, and considers "road" and "country" to be synonymous.

Under the ancient Ritsuryo system, seven roads radiated from Kyoto, including the Sanyo, Tosan, Tokai, Hokuriku, San'in, Nankai, and Saikai, and formed the core of Japan's transportation system. Of these, the most important were the Sanyo, which connected Kyoto with Dazaifu, and its extension, the Saikai, which was called the "Oji" (Great Road), followed by the Tozan and Tokai roads as the "Chuji" (Middle Road), and the four roads below the Hokuriku road, as well as the roads of Ise, Yamato, Mimasaka, Hida, Echigo, Kai, Kazusa, and Dewa, were called the "Koji" (Little Road). Along these seven roads and their branch lines, the post roads, stations were set up, in principle, every 30 ri (at the time 1 ri = 6 cho, so 5 ri in early modern times, about 20 km today), and station horses (20 for main roads, 10 for middle roads, and 5 for small roads) were always kept on hand, and the station master supervised the station boys, taking care of the transfer of horses and riders, providing rest and meals, etc. In addition, instead of post horses, water stations were always kept on hand, with ferry boats and ferrymen, and station masters were stationed just like land stations. While the post roads connected the provincial capitals, the roads connecting the provincial capitals with the county offices (gunga) were of the next highest importance, and each county office was provided with official horses called denma. With the decline of the Ritsuryo system, the functions of stations in this transportation system also declined, and from the end of ancient times onwards, transportation settlements were established and developed, centered around commercial inns called shuku, on the Tokaido road and other roads, instead of stations.

When the Kamakura Shogunate was established in the early Middle Ages, the transportation system that had been centered on the Sanyo Road was significantly altered, and the Tokaido Road connecting Kyoto and Kamakura was elevated to the foremost trunk road in Japan. In this case, the new Tokaido Road in the Middle Ages avoided the difficult crossing of the Ise-Suzuka Pass and passed through the ancient Tosando Road and the Tokai-Higashiyama Link Road (later the Mino Road), and there were many other partial changes to the route. On the other hand, there seem to have been many inns along the original route of the Sanyo Road, but the use of sea routes became an obstacle to its development. The San'in Road came to be used more as a link between the San'yo and San'in roads than as a link between the east and west of the ancient official road, and on the extension of the Hokuriku Road, inns that followed the station system were run by local feudal lords, and it is said that the Kamakura Shogunate's land stewards stationed night watchmen to guard them. The ancient Nankaido was a pilgrimage route to Kumano until the first half of the Middle Ages, and changed to a pilgrimage route to Ise from the second half onwards, but on the Saikaido, Dazaifu and Hakata were nodes to Honshu and other areas, while many ancient main roads were used as marching routes for warlords in the west. In the Kanto region (15 provinces), which was the main base of the Kamakura Shogunate, the Kamakura Kaido was opened, connecting Kamakura with the bases of local samurai, and main roads and branch roads from various provinces were concentrated there. After the establishment of the Muromachi Shogunate, there were some changes in this transportation system, but when the Sengoku daimyo established their bases in various regions, the transportation system of the early and mid-Medieval period collapsed significantly, and highways and denma systems were formed within the territories of the Sengoku daimyo in a sequence of main castles - secondary castles - rural areas.

The unification of Japan by Toyotomi Hideyoshi in the early modern period laid the foundation for a network of highways throughout the country, from Oshu in the north to Kyushu in the south. Tokugawa Ieyasu further implemented the telegraph system on the Tokaido road in 1601 (Keicho 6) after the Battle of Sekigahara, and from the following year he successively implemented this system on the Nakasendo road, Nikko, Oshu, and Koshu roads, resulting in the establishment of five highways and their post stations centered on Edo. The Five Highways were the most important roads that ran through central Honshu, starting from Edo Nihonbashi. They were generally referred to as the Tokaido (Shinagawa-Otsu, extended to Moriguchi), Nakasendo (Itabashi-Moriyama), Nikko Dochu (Senju-Hachiishi), Oshu Dochu (Shirasawa-Shirakawa), and Koshu Dochu (Naito-Shinjuku or Kamitakaido-Kamisuwa). The Tokaido was supplemented by the Mino Road, Saya Road, and Honzaka Street, and the Nikko Dochu included the Mibu Road, Mito-Sakura Road, and Reiheishi Kaido. The shogunate's road magistrate (bugyo) had direct control over these five highways and their supplementary roads. However, regarding the routes of the Five Highways, there are theories that exclude the Oshu and Koshu Highways and include the Mito Highway and the Hokuriku Highway, as well as the theory that adds the Mito and Sakura Highways to the aforementioned Five Highways to make a total of Seven Highways.

The main roads that were extensions of the Five Highways were called side roads or side routes, but in this case the Shogunate's Finance Magistrate was only indirectly involved, and in principle local authorities (gundai and magistrates in the Tenryo domain, feudal domains in private domains, etc.) controlled them directly. The main side roads were the Sado Road (Aizu-dori, Mikuni-kaido, and Hokkoku-kaido) in central Honshu, as well as the Sendai-Matsumae Road, Ushu-kaido, Hokkoku-ji, Iga-goe Dochu, Ise-ji, Chugoku-ji, and Nagasaki-ji from the north, and a unique one was the Godai-san Road (a road from Tsuchiyama on the Tokaido to Echigawa on the Nakasendo. The Imperial Court had its representatives visit Taga Shrine in Omi). In remote areas that had no direct connection to the Five Highways, the Waki-kaido was generally the main road, and it was not uncommon for several Naka-kaido (side roads) to radiate out from the castle towns connected to it within the domain, forming the so-called Mini Five Highways. And while this relationship between the Five Highways and the Waki-kaido symbolized the relationship between the shogunate and the domain, it also stood at the top of a multi-layered transportation system in the various domains, which consisted of the main Waki-kaido - Naka-kaido - village road - farmer's road.

[Yoshinari Maruyama]

"Kodama Kota and Toyoda Takeshi eds., Systematic Japanese History Series 24: Transportation History" (1970, Yamakawa Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

国中に通ずる官道、または主要な陸路。海道とも書く。街道の始源については、すでに大和(やまと)朝廷の成立後、大和を中心に山陽道、東海道、南海道が開かれたといわれるが、『日本書紀』は、崇神(すじん)天皇のときに北陸、東海、西道、丹波(たんば)に四道将軍が派遣されたことを記し、『古事記』にも、高志道(こしじ)、東方十二道、丹波国におのおの派遣されたという記事がある。この点について、『古事記伝』（本居宣長(もとおりのりなが)）は、前記の西道を山陽道として、西海道までさすものとはせず、また高志道を越国(こしのくに)、東方十二道を東方十二国として、「道」と「国」とは同義語とする。

　古代の律令(りつりょう)制下では、京を中心として山陽道、東山道(とうさんどう)、東海道、北陸道、山陰道、南海道、西海道の七道が発し、わが国の交通体系の中核を形づくった。このうちもっとも重要視されたのは、京―大宰府(だざいふ)間を結ぶ山陽道と、その延長である西海道の一部で、これを大路とよび、これに次ぐ東山・東海両道を中路、そして北陸道以下の四道および伊勢(いせ)、大和、美作(みまさか)、飛騨(ひだ)、越後(えちご)、甲斐(かい)、上総(かずさ)、出羽(でわ)の各路を小路とよんだ。これら七道とその支線である駅路には、原則として30里（当時は1里＝6町なので、近世の5里、現在の約20キロメートル）ごとに駅を配置したが、そこでは駅馬（大路20疋(ひき)、中路10疋、小路5疋）を常備し、駅長が駅子を指揮して人馬の継立(つぎたて)や休泊、給食などにあたった。なお、水駅には、駅馬のかわりに渡船(わたしぶね)、渡守(わたしもり)を常備して、陸駅と同じく駅長が置かれた。駅路が国府を連絡するものであったのに対し、国府と郡家（郡衙(ぐんが)）とを結ぶ道もこれに次ぐ重要なもので、各郡家には伝馬という官馬が用意されていた。こうした交通体系も、律令制の衰退とともに駅の機能が低下し、古代末期以降は駅にかわって、東海道などでは宿(しゅく)とよばれる営業的旅舎を中核とした交通集落が成立、発展していった。

　中世初期、鎌倉幕府が成立すると、従来の山陽道中心の交通体系は大きく改変して、京―鎌倉を結ぶ東海道をわが国第一の幹線道路に引き上げることとなった。この場合、中世の新しい東海道は、伊勢鈴鹿(すずか)峠越えの難所を回避して、古代の東山道と東海・東山連絡路（後の美濃路(みのじ)）を通過しており、そのほかにもコースに部分的変更のあるところが少なくない。一方、山陽道は、従来の路線上に多く宿が存在したようであるが、海路の利用はその発展の阻害要因となった。山陰道は、古代の官道による東西の連絡よりも、山陽・山陰両道間の連絡路が多用されるようになったし、北陸道の延長では、駅制を踏襲した宿が地方豪族の手で経営され、鎌倉幕府の地頭(じとう)が宿直人を配置して警固したという。古代の南海道は中世前半まで熊野参詣(さんけい)の道、後半以降は伊勢参詣の道へと変化したが、西海道では大宰府、博多(はかた)が本州などとの結節点となる一方では、西国武将の行軍路に多く古代以来の幹線路が利用されていた。なお、鎌倉幕府のおもな基盤である関東御分国（15か国）では、鎌倉と地方武士の本拠地とを結ぶ鎌倉街道が開かれて、諸国からの本道や分岐道が集中した。室町幕府の成立後、こうした交通の様相には多少の変化も生じたが、戦国大名が各地に割拠する段階では、中世前・中期の交通体系は大きく崩れて、戦国大名の領国内には本城―支城―農村の系列で街道や伝馬制が形成されていった。

　近世初頭の豊臣(とよとみ)秀吉による天下統一は、北は奥羽から南は九州まで全国の街道を貫通させる基礎を固めたが、さらに徳川家康が関ヶ原の戦い後の1601年（慶長6）東海道の伝馬制を実施し、その翌年以降に中山道(なかせんどう)以下、日光、奥州、甲州道中に順次これを施行するに及び、江戸を中心とする五街道とその宿駅が成立した。五街道は、江戸日本橋を起点として本州中央部を走るもっとも重要な街道で、一般に東海道（品川―大津、延長して守口(もりぐち)）、中山道（板橋―守山(もりやま)）、日光道中（千住(せんじゅ)―鉢石(はちいし)）、奥州道中（白沢―白川）、甲州道中（内藤新宿(ないとうしんじゅく)または上高井戸(かみたかいど)―上諏訪(かみすわ)）をさすが、東海道には美濃路、佐屋路(さやじ)、本坂通(ほんざかどおり)、日光道中には壬生(みぶ)通、水戸・佐倉道、例幣使(れいへいし)街道が付属し、幕府の道中奉行(ぶぎょう)がこの五街道と付属街道を直接支配した。もっとも、五街道の道筋については、奥州・甲州両道中を除いて水戸道中、北陸道をあげる説や、前記の五街道に水戸・佐倉両道中を加えて七街道とする説などもある。

　五街道を延長した主要な街道を脇(わき)街道、脇往還というが、ここでは幕府の勘定奉行は間接的に関与するにとどまり、在地の権力（天領は郡代や代官、私領は藩など）が直接支配するのが原則であった。おもな脇街道として、本州中央部の佐渡路(さどじ)（会津通、三国(みくに)街道、北国(ほっこく)街道の三道）のほか、北から仙台・松前道、羽州街道、北国路、伊賀越(いがごえ)道中、伊勢路、中国路、長崎路などがあげられ、特殊なものに御代参(ごだいさん)街道（東海道の土山(つちやま)から中山道の愛知(えち)川に至る街道。朝廷が名代を近江(おうみ)の多賀神社に参詣させた）がある。五街道と直接の関係をもたない遠隔地の場合、一般に脇街道が主幹線であって、これが連絡する城下町からは、さらに藩領内に幾筋かの中街道（脇道）を放射状に発して、いわゆるミニ五街道を形成することもまれではなかった。そして、この五街道―脇街道の関係は、幕府―藩の関係を象徴する側面をもつ一方で、諸藩における主要な脇街道―中街道―村道―農民の生活道といった、重層的な交通体系の頂点にたつものでもあった。

［丸山雍成］

『児玉幸多・豊田武編『体系日本史叢書24　交通史』（1970・山川出版社）』

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