The Chigasaki to Samukawa section was opened by the
Sagami Railway (Sōtetsu) in 1921, primarily to haul gravel. The line was extended to Atsugi in 1926, and to Hashimoto in 1931. The line was nationalized in 1944 during
World War II; the private Sagami Railway began operating the then , now the
Sagami Railway Main Line. A short branch to Nishi-Samukawa Station from Samukawa Station was closed in 1984, and freight services ceased in 1998. After privatization of
Japanese National Railways (JNR) in 1987, the line was electrified in 1991. Before the JNR privatization, there were discussions to transfer the line to the Sagami Railway in order meet the expected demands of passenger traffic in the Tokyo and Yokohama suburbs. Because it had long been left as a non-electrified rural line, the cost to upgrade the line was beyond the ability of then financially constrained JNR; Sagami Railway, on the other hand, was running a profitable operation on its own line. However, the two companies did not agree on a deal, and plans to transfer the line were cancelled. Upon electrification, through services to the
Yokohama Line began, using the new
205-500 series EMUs. The through service operation ended on 11 March 2022. ==References==