The Tokaido Line
The Tōkaidō Main Line is the busiest trunk line of the Japan Railways Group, connecting Tokyo and Kōbe stations. It is 589.5 km long, not counting its many freight feeder lines around the major cities. It runs 713.6 km including branch and feeder lines. It is run in cooperation with three railway companies: JR East, JR Central and JR West.
Its namesake comes from the ancient road connecting the Kansai region (Kyoto, Osaka) with the Kantō region (Tokyo, formerly Edo) through the Tōkai region (including Nagoya.) Literally, it was called the Tōkai road, or "Road through Tōkai." When rail service was introduced to Japan in the late 1800s, one of the priorities of planners was to build a line between Tokyo and Osaka, roughly following the old Tokaido road.
The first railway in Japan was the route from Shinbashi in Tokyo to Sakuragicho in Yokohama, which opened in 1872; another segment of today's Tokaido Main Line, between Kyoto and Kobe, opened in 1877. Other sections were laid and the first complete line from Tokyo to Kobe was completed in 1889, with a train between Tokyo to Kobe taking 20 hours at the time. In 1930 the first express train, called the Tsubame ("swallow") was introduced. The express reduced travel time from Tokyo to Kobe down to nine hours, a significant reduction.
The Shinkansen bullet train which opened in 1964 follows many parts of the same path and shaved travel time between Tokyo to Kobe down to four hours. Improved bullet train technology has pared that down to three hours at present.
Although the route accounts for only 3 percent of Japan's rail line by distance, it accounts for over 25% of all passenger and freight traffic in the country.
Stations along the Tokaido line can be found here (the JR site, in Japanese): http://www.jreast.co.jp/estation/result.aspx?mode=2&rosen=49=1=%93%8C%8AC%93%B9%96%7B%90%FC