Tobu Kinugawa Line

The line began not as a railway but as a narrow-gauge industrial tramway. A 762 mm gauge horse- and steam-worked tramway was opened in the area to haul materials for power-station construction, and the enterprise that would become the Kinugawa Line was promoted under the name Shimotsuke Tramway (下野軌道), incorporated in 1915. The first public section, from Ōtani-mukō (in Imaichi) to Nakaiwa, opened on 2 January 1917 as a steam-hauled 762 mm gauge tramway. Spurred by a local mining boom, the line was extended in stages through 1917 and 1919, and on 1 January 1920 the through route from Shin-Imaichi to Fujiwara — about 16 km — was completed.

The operator was reorganised as the Shimotsuke Electric Railway (下野電気鉄道) on 6 June 1921, and on 9 March 1922 the whole line was electrified at 600 V DC and shifted from the light-railway (tramway) framework to the railway framework, with several stations renamed in the process. Through the 1920s the company added and renamed stations as the hot-spring resort grew: the station serving the springs was renamed Kinugawa Onsen in 1927.

Two decisive upgrades followed at the end of the decade. From 22 October 1929 the line was progressively converted from 762 mm to 1,067 mm gauge — the change beginning at the southern end, where the realigned route was tied directly into the Tobu Nikkō Line at Shimo-Imaichi — and the conversion was completed to Shin-Fujiwara on 9 May 1930. On 1 March 1931 the supply voltage was raised from 600 V to 1,500 V, bringing the line up to the standard of the larger Tobu network it would soon join.

On 1 May 1943 the Shimotsuke Electric Railway was absorbed by Tobu Railway, and the route took its present identity as the Tobu Kinugawa Line. As a Tobu line it became the resort tail of long-distance limited-express services from the Tokyo end: a seasonal limited express to Kinugawa Onsen ran from 1948, and the "Kinu" express name, later written in hiragana as "Kinu," was introduced in 1949. Over the following decades stations were opened, suspended, relocated and closed as wartime austerity, resort tourism and line improvements came and went; in 1964 the former Kinu-Tateiwa station became a signal point and Kinugawa Onsen station was relocated, the short double-track section dating from this work.

The line's reach northward was extended by third-sector connections. On 9 October 1986 the Yagan Railway Aizu Kinugawa Line opened beyond Shin-Fujiwara and through services with Tobu began, and from 12 October 1990 those services were extended over the newly electrified Aizu Railway Aizu Line toward Aizu-Tajima. At the Tokyo end, direct limited expresses to and from Shinjuku over JR tracks — the "Nikkō" and "Kinugawa"/"Spacia Kinugawa" services — were inaugurated on 18 March 2006, giving the onsen resort a one-seat link to central Tokyo via JR as well as Tobu's own Asakusa route. Tobu-wide station numbering, with the orange "TN" prefix, was applied from 17 March 2012.

In the 2010s the line was developed as a heritage and sightseeing route. Tōbu World Square Station opened on 22 July 2017, and on 10 August 2017 Tobu inaugurated the "SL Taiju" steam service, hauling a restored former JNR Class C11 locomotive (C11 207, leased from JR Hokkaido; the JA source notes C11 325 was later added) over the roughly 12.4 km between Shimo-Imaichi and Kinugawa Onsen, with new turntables and an engine shed built to support it. A diesel-hauled "DL Taiju" complement followed in 2020. Today the Kinugawa Line carries a mix of local trains and tourist limited expresses, and the SL Taiju has made it one of the best-known steam-operated lines in the Kantō region.

• 1915Shimotsuke Tramway (下野軌道) is incorporated to build a 762 mm gauge tramway in the Kinugawa area (succeeding an industrial tramway used for power-station construction).
• 19172 January: the first section, Ōtani-mukō to Nakaiwa (4.9 km), opens as a steam-hauled 762 mm gauge tramway.
• 19201 January: the Shin-Imaichi–Fujiwara through line (about 16 km) is completed after stage-by-stage extensions through 1917–1919.
• 19216 June: the operator is reorganised as the Shimotsuke Electric Railway (下野電気鉄道).
• 19229 March: the whole line is electrified at 600 V DC and converted from the tramway framework to the railway framework; several stations are renamed.
• 192719 February: the station serving the hot springs (former Ōtaki) is renamed Kinugawa Onsen.
• 192922 October: gauge conversion from 762 mm to 1,067 mm begins at the southern end, with the realigned route tied directly into the Tobu Nikkō Line at Shimo-Imaichi.
• 19309 May: the gauge conversion to 1,067 mm is completed through to Shin-Fujiwara.
• 19311 March: the supply voltage is raised from 600 V to 1,500 V DC.
• 19431 May: the Shimotsuke Electric Railway is purchased by Tobu Railway; the route becomes the Tobu Kinugawa Line.
• 19648 October: Kinu-Tateiwa station becomes a signal point and Kinugawa Onsen station is relocated; the 0.8 km double-track section dates from this work.
• 19869 October: the Yagan Railway Aizu Kinugawa Line opens beyond Shin-Fujiwara and through services with Tobu begin.
• 199012 October: through services are extended over the newly electrified Aizu Railway Aizu Line toward Aizu-Tajima.
• 200618 March: direct limited expresses to/from Shinjuku over JR tracks ("Nikkō" and "Kinugawa"/"Spacia Kinugawa") are inaugurated.
• 201217 March: Tobu-wide station numbering is introduced, the Kinugawa Line taking the orange "TN" prefix.
• 201722 July: Tōbu World Square Station opens; 10 August: the "SL Taiju" steam service begins, hauling former JNR Class C11 locomotive C11 207 (leased from JR Hokkaido) over the ~12.4 km Shimo-Imaichi–Kinugawa Onsen section.