The Tōkaidō Main Line (Japanese: 東海道本線, romanized: Tōkaidō-honsen) is one of the most important railway corridors in Japan, connecting the major cities of Tokyo and Kobe via Shizuoka, Nagoya, Kyoto and Osaka.

Today, the only daily passenger train that travels the entire length of the line is the combined Sunrise Izumo/Sunrise Seto service which runs overnight.

Japan's largest population centers are all along this route: Tokyo, Yokohama, Nagoya, Kyoto, Osaka, and Kobe.

Since construction of the line, these centers have since grown to occupy an ever more dominant role in the country's government, financial, manufacturing, and cultural life.

[2] In 1883, the government decided to use the Nakasendō route, and construction of several segments commenced (including the modern-day Takasaki Line).

Railways were opened between Ogaki and Nagahama (1884) and between Nagoya and Kisogawa (1886) in line with the Nakasendo plan.

In October 1895, following the Sino-Japanese War, through service to the Sanyo Railway (now the San'yō Main Line) began.

In 1906, all privately run main lines were nationalized under the newly created Japanese Government Railways, which at the time had a network of just over 7,000 km (4,300 mi) of track.

[1]By the start of the Taishō era, route changes on several stretches of the line were deemed necessary to accommodate growing demand.

The mountainous Gotemba stretch required an even larger-scale route change, culminating in the completion of the Tanna Tunnel in 1934 after 15 years of construction.

Commuter rapid services between Kyoto and Kobe, using 52 Series streamliner EMUs, began in 1937.

JNR Class D52 locomotives were introduced for wartime freight transport, but their poor manufacturing quality led to several boiler explosion accidents.

[7] In the immediate aftermath of the war, almost all surviving express train carriages were requisitioned by the Allied Occupation Forces.

Express trains for Japanese nationals resumed in April 1947, with sleeper services following in July 1948.

One of the C62s, C62 17, holds the narrow-gauge steam world speed record, which was achieved on the Tokaido line near Nagoya on 15 December 1954, and is preserved at the SCMaglev and Railway Park.

[11] On 1 October 1958, the Kodama, the first limited express service operated by EMUs rather than locomotive-hauled carriages, commenced.

On the same day, the Asakaze sleeper express entered service with the newly built Series 20 carriages.

Intercity passenger traffic between Tokyo, Nagoya and Osaka largely transferred to the Tōkaidō Shinkansen after it was completed in 1964.

Following the Hanshin earthquake on 17 January 1995, the line was shut down between Takatsuki and Kobe, with certain segments remaining impassable until 1 April of that year.

In 1944, a single track bypass (in brown on the diagram) was built to avoid this steep slope of the main line.

Although Kōbe is the official terminus of the Tōkaidō Main Line, most trains continue to Nishi-Akashi, Himeji and beyond.