The Shinonoi to Nishijo section opened in 1900, and was extended via Matsumoto to Shiojiri in 1902.[citation needed]
The Shiojiri to Matsumoto section was double-tracked between 1961 and 1965, with the Tazawa to Akashina section double-tracked in 1966. The Akashina to Nishijo section was also double-tracked, but the original line was decommissioned in 1988.[citation needed]
The Shiojiri to Matsumoto section was electrified in 1964/5, and extended to Shinonoi in 1973, CTC signalling being commissioned on the entire line the previous year.[citation needed]
Former connecting lines
Matsumoto Station: The Chikuma Electric Railway opened a 5 km line, electrified at 600 V DC, to Asama Onsen in 1924. In 1958 the voltage was raised to 750 V DC, but the line closed in 1964.[citation needed]