Toyohashi Railroad Atsumi Line

Proposals to build a railway across the Atsumi Peninsula date back to the period after the Imperial Army's 15th Division was stationed at Toyohashi. In 1909 a group of twelve people, with the financial backing of Keijirō Amemiya, planned a light railway, but the scheme was not built. Local promoters established the Amami Light Railway in 1918, and the privately owned Atsumi Electric Railway (渥美電鉄) was founded in 1919 to carry the project forward.

The Atsumi Electric Railway opened its first section, between Takashi and Toyoshima, on 22 January 1924, electrified at 600 V DC. Extensions followed rapidly the same year: to Kambe in March and on to Tahara — today's Mikawa-Tahara — by 10 June 1924. Building in the opposite direction toward Toyohashi, the company reached the first Shin-Toyohashi terminus in May 1925, and on 1 October 1927 a final link from Toyohashi-Ekimae brought trains up to the JR station forecourt, completing the through line on 11 October 1927.

The railway continued to grow into the late 1920s. On 10 April 1926 a now-defunct section was opened beyond Tahara to Kurokawahara, extending the line deeper into the peninsula. A further extension toward Mikawa-Fukue, at the peninsula's tip, was licensed but never completed; construction begun toward the end of the 1930s was abandoned under the pressures of the Second World War.

The wartime years brought contraction and tragedy. On 1 September 1940 the Atsumi Electric Railway was absorbed by Nagoya Railroad (Meitetsu), and the route became Meitetsu's Atsumi Line. With steel in short supply, the Mikawa-Tahara–Kurokawahara section and a number of stations were suspended on 5 June 1944. On 14 August 1945, one day before Japan's surrender, three North American P-51 Mustang aircraft strafed a Toyohashi-bound train near Tenpaku, killing fifteen people and injuring sixteen more.

On 1 October 1954 Meitetsu spun the Shin-Toyohashi–Mikawa-Tahara section off to the newly formed Toyohashi Railroad, which has operated the line ever since; the suspended Mikawa-Tahara–Kurokawahara section was formally abandoned the following month. Under Toyotetsu the line settled into its role as a local commuter and student railway: express services were introduced on 1 October 1965, running eighteen times a day, before being withdrawn on 1 September 1985, and all freight operations ended on 1 February 1984.

The modern line took shape in the late 1990s. On 2 July 1997 the overhead voltage was raised from 600 V to 1,500 V DC and the entire fleet was replaced with twenty-eight former Meitetsu 7300-series cars, all air-conditioned. From 2000 the railway began introducing 1800-series trains rebuilt from former Tōkyū 7200-series stock, and these now make up the whole fleet, running as three-car sets. Since January 2013 they have been operated as "Colorful Trains," each set painted in an image colour and carrying a headmark themed on one of the flowers representative of the Atsumi Peninsula. Cycle trains, which allow passengers to board with their bicycles, began on weekends and holidays in September 2011 and were extended to weekdays in July 2017.

• 1919The privately owned Atsumi Electric Railway (渥美電鉄) is established to build a railway across the Atsumi Peninsula (a local Amami Light Railway had been formed in 1918).
• 192422 January: the Atsumi Electric Railway opens its first section, Takashi–Toyoshima, electrified at 600 V DC; extensions reach Kambe in March and Tahara (now Mikawa-Tahara) by 10 June.
• 19251 May: the line is extended in the Toyohashi direction, reaching the first Shin-Toyohashi terminus (from Shidanguchi).
• 192610 April: the now-defunct section from Mikawa-Tahara to Kurokawahara opens, extending the line deeper into the peninsula.
• 19271 October: the final link from Toyohashi-Ekimae to the first Shin-Toyohashi opens, completing the through line on 11 October; the terminus is renamed Shin-Toyohashi (2nd) on 13 October.
• 19401 September: the Atsumi Electric Railway is merged into Nagoya Railroad (Meitetsu) and the route becomes Meitetsu's Atsumi Line.
• 19445 June: amid wartime steel shortages, Meitetsu suspends the Mikawa-Tahara–Kurokawahara section and a number of stations.
• 194514 August: one day before Japan's surrender, three North American P-51 Mustang aircraft strafe a Toyohashi-bound train near Tenpaku, killing 15 people and injuring 16.
• 19541 October: Meitetsu transfers the Shin-Toyohashi–Mikawa-Tahara section to the newly formed Toyohashi Railroad; the suspended Mikawa-Tahara–Kurokawahara section is formally abandoned on 20 November.
• 19651 October: a timetable revision introduces express services running 18 times a day.
• 19841 February: all freight operations on the line are discontinued.
• 19851 September: express services are abolished.
• 19972 July: the overhead voltage is raised to 1,500 V DC and the whole fleet is replaced with 28 former Meitetsu 7300-series cars, all air-conditioned.
• 200022 December: 1800-series trains rebuilt from former Tōkyū 7200-series stock enter service; they later make up the entire fleet and, from January 2013, run as flower-themed 'Colorful Trains'.