Toyamakō Line

The route was opened on 23 July 1924 by the privately owned Fugan Railway (富岩鉄道), which ran a passenger line between Toyamaguchi and Iwasekō, a distance of about 7.56 km (then measured as 4.7 miles). A short freight branch from Toyama to Toyamaguchi opened in 1927, and passenger services were extended over it to Toyama Station in 1928, while further freight branches toward the harbour district were added through the 1930s. In 1941 the Fugan Railway transferred its lines to the Toyama Electric Railway and was dissolved, the route becoming that company's Fugan Line (富岩線).

On 1 January 1943 the Toyama Electric Railway renamed itself the Toyama Chihō Railway, and on 1 June 1943 the Toyama–Iwasehama route, together with associated branches, was nationalised under the wartime buy-out of private railways and renamed the Toyamakō Line. Because of this private origin the line was electrified on direct current while the connecting Hokuriku Main Line at Toyama used alternating current; the Toyamakō Line remained the only DC-electrified national/JR line in the Hokuriku region until the Nanao Line was electrified on DC in 1991. The line's overhead voltage was raised from 600 V to 1,500 V DC on 30 March 1967, the last of the privately built lines bought out by JNR to be so upgraded.

Under Japanese National Railways the Toyamakō Line was a self-contained commuter line of local trains shuttling within the section, serving central Toyama and lineside factories. The line's freight branches were progressively closed in the 1980s, and the older 72-series electric multiple units ran until the timetable revision of 14 March 1985, after which the line shared AC/DC rolling stock with the Hokuriku Main Line. On 1 April 1987, with the privatisation of JNR, the line passed to the West Japan Railway Company (JR West). During the JR West years ridership declined steadily, and from 2001 diesel railcars (KiHa 120) were introduced for daytime and evening services to economise on off-peak operation, sharing duties with the Takayama Main Line.

From around 2003 JR West made public that it was studying converting the Toyamakō Line, along with the Kibi Line, into a light-rail (LRT) operation. The plan was driven by a project to elevate Toyama Station for the coming Hokuriku Shinkansen: grade-separating the lightly used Toyamakō Line was poor value for money, and outright closure had even been considered, but the lineside had become urbanised and bus substitution carried large drawbacks. It was decided that a third-sector company centred on the City of Toyama would take the line over, and Toyama Light Rail Co., Ltd. (富山ライトレール) was established on 21 April 2004. The plan added a new section of street track at the Toyama-Station end, abolished Toyamaguchi Station, and inserted several new stops.

JR West operation ended with the last train on 28 February 2006 (the line being formally abolished the next day), after which buses substituted for about two months. Toyama Light Rail began operating the reopened line on 29 April 2006, the overhead being reduced back to 600 V DC in anticipation of future through-running onto the 600 V Toyama tram network; new low-floor light-rail vehicles, the TLR0600 type nicknamed "Portram", were introduced. The conversion was Japan's first full LRT conversion of an existing heavy-rail line, and it drew immediate use — 12,750 people are reported to have ridden on the first day, and one million passengers had used the line by 9 November 2006. New double-tracking and additional stops followed in later years.

On 22 February 2020 Toyama Light Rail was absorbed into the Toyama Chihō Railway, returning the line to its pre-war operator after 77 years and 8 months — described as the first case in Japan of a nationalised railway reverting to its original operator. On 21 March 2020, with the completion of a new north–south tram link across Toyama Station, the former Toyama-Eki-Kita stop was merged into the Toyama Station stop and through-running with the Toyama Chihō Railway tram (Toyama Tramway) network began, with vehicles working across both systems. Further street-track stops were added in March 2021, and nationally interoperable IC cards became usable on the line from October 2021.

• 192423 July: the Fugan Railway opens the line as a passenger railway between Toyamaguchi and Iwasekō (about 7.56 km).
• 192811 July: passenger services begin on the Toyama–Toyamaguchi section, extending the line to Toyama Station.
• 19381 January: Iwasekō Station is renamed Iwasehama, the line's present northern terminus.
• 19411 December: the Fugan Railway transfers the line to the Toyama Electric Railway and is dissolved; it becomes the Fugan Line.
• 19431 January: the Toyama Electric Railway is renamed the Toyama Chihō Railway. 1 June: the Toyama–Iwasehama route is nationalised under the wartime buy-out of private railways and renamed the Toyamakō Line.
• 196730 March: the overhead voltage is raised from 600 V to 1,500 V DC — the last JNR buy-out line to be upgraded.
• 198514 March: with a timetable revision the 72-series electric multiple units are withdrawn and rolling stock is shared with the Hokuriku Main Line.
• 19871 April: with the privatisation of JNR, the line passes to the West Japan Railway Company (JR West).
• 20013 March: KiHa 120 diesel railcars are introduced for daytime and evening services and one-man operation begins.
• 200421 April: Toyama Light Rail Co., Ltd. is established to take over and convert the line to light rail.
• 200628 February: JR West operation ends with the last train (line abolished the next day). 29 April: Toyama Light Rail begins operating the reopened line, the overhead reduced to 600 V DC; new 'Portram' light-rail vehicles enter service in Japan's first full LRT conversion of an existing JR line. 12,750 people are reported to have ridden on the first day.
• 20069 November: one million passengers have used the converted line.
• 20184 March: the Hatta-bashi-Higashizume–Okuda-Chūgakkō-mae section is double-tracked.
• 202022 February: Toyama Light Rail is absorbed into the Toyama Chihō Railway, returning the line to its pre-war operator after 77 years 8 months — said to be the first case in Japan of a nationalised railway reverting to its original operator.
• 202021 March: with a new north–south tram link across Toyama Station, the Toyama-Eki-Kita stop is merged into the Toyama Station stop and through-running with the Toyama Chihō Railway tram network begins.
• 202110 October: nationally interoperable transit IC cards (such as ICOCA) become usable on the line.