Sasshō Line

The line was built in two halves under Japanese Government Railways. The Sasshō North Line opened first, between Ishikari-Numata and Nakatoppu, on 10 October 1931, and was extended south from Nakatoppu to Urausu exactly three years later, on 10 October 1934. The Sasshō South Line opened from Sōen to Ishikari-Tōbetsu on 20 November 1934. The two halves were joined when the Ishikari-Tōbetsu–Urausu section opened on 3 October 1935, completing a through route between Sōen and Ishikari-Numata; on the same day the unified line was given the name Sasshō Line.

The Second World War nearly erased the line. As a duplicate route paralleling the Hakodate Main Line, much of it was designated a "non-urgent line" (不要unnecessary wartime category) and its rails were lifted for the war effort: the Ishikari-Tsukigata–Ishikari-Oiwake section was suspended on 1 October 1943, and the Ishikari-Tōbetsu–Ishikari-Tsukigata and Ishikari-Oiwake–Ishikari-Numata sections followed on 21 July 1944. Restoration came only gradually after the war. The Ishikari-Tōbetsu–Urausu section reopened on 10 December 1946, the line was transferred to the new Japanese National Railways (JNR) on 1 June 1949, the Urausu–Uryū section reopened on 3 November 1953 — the same day Nakatoppu Station was renamed Shin-Totsukawa — and the final Uryū–Ishikari-Numata stretch reopened on 16 November 1956, restoring service over the whole line.

Low ridership soon put the rural northern half under pressure. The thinly used Shin-Totsukawa–Ishikari-Numata section was abolished on 19 June 1972 after the four lineside towns agreed to its closure, leaving the line running from Sōen only as far as Shin-Totsukawa. Through the JNR era the southern end of the line was steadily modernised, gaining new stations and centralised traffic control as Sapporo's suburbs spread northward along it.

With the privatisation of JNR on 1 April 1987, the Sasshō Line passed to JR Hokkaido. The nickname "Gakuentoshi Line" was formally adopted on 16 March 1991, reflecting the line's role as a commuter route to the universities and colleges on Sapporo's northern fringe. Through the 1990s and 2000s the busy Sapporo-end section was double-tracked in stages between Hachiken and Ainosato-Kyōikudai, several stations were renamed and elevated, and one-man operation, station numbering and the Kitaca IC card were introduced.

The line's defining modern change was electrification. JR Hokkaido announced the project in 2009 and began work that December; the AC electrified service between Sōen and Hokkaidō-Iryōdaigaku opened on 1 June 2012, with some trains converted to electric multiple units, and from the timetable revision of 27 October 2012 all scheduled trains on the section ran as EMUs. The non-electrified single-track section north of Hokkaidō-Iryōdaigaku, by contrast, kept its diesel railcars and its dwindling ridership.

That northern remnant was the next to go. After years of discussion, JR Hokkaido and the four lineside towns agreed in December 2018 to abolish the Hokkaidō-Iryōdaigaku–Shin-Totsukawa section, and a closure notice was filed with the transport minister. The shutdown was originally scheduled for 7 May 2020, but the company brought the last day of operation forward to 17 April 2020 amid the COVID-19 outbreak, cancelling the planned farewell runs; the section was formally abolished on 7 May 2020. With that, the Sasshō Line was reduced to its present electrified 28.9 km between Sōen and Hokkaidō-Iryōdaigaku. In a later change, Royce' Town Station opened on 12 March 2022 and Ishikari-Tōbetsu and Ishikari-Futomi stations were renamed Tōbetsu and Futomi.

• 193110 October: the Sasshō North Line opens between Ishikari-Numata and Nakatoppu.
• 193410 October: the North Line is extended from Nakatoppu to Urausu. 20 November: the Sasshō South Line opens between Sōen and Ishikari-Tōbetsu.
• 19353 October: the Ishikari-Tōbetsu–Urausu section opens, joining the two halves into a through route; the unified line is named the Sasshō Line.
• 19431 October: the Ishikari-Tsukigata–Ishikari-Oiwake section is designated a non-urgent wartime line and suspended.
• 194421 July: the Ishikari-Tōbetsu–Ishikari-Tsukigata and Ishikari-Oiwake–Ishikari-Numata sections are likewise suspended as non-urgent wartime lines.
• 194610 December: the Ishikari-Tōbetsu–Urausu section reopens after the war.
• 19491 June: the line is transferred to the newly formed Japanese National Railways (JNR).
• 19533 November: the Urausu–Uryū section reopens and Nakatoppu Station is renamed Shin-Totsukawa.
• 195616 November: the Uryū–Ishikari-Numata section reopens, restoring service over the whole line.
• 197219 June: the lightly used Shin-Totsukawa–Ishikari-Numata section is abolished after the four lineside towns agree to its closure.
• 19871 April: JNR is privatised and the Sasshō Line passes to JR Hokkaido.
• 199116 March: the nickname "Gakuentoshi Line" is formally adopted.
• 20121 June: the Sōen–Hokkaidō-Iryōdaigaku section opens under AC electrification, with some trains converted to electric multiple units; from the 27 October timetable revision all scheduled trains on the section run as EMUs.
• 20207 May: the non-electrified Hokkaidō-Iryōdaigaku–Shin-Totsukawa section is formally abolished; the last day of operation had been brought forward to 17 April due to the COVID-19 outbreak, cancelling the planned farewell runs.