The Uchibō line began operation in 1912, and was originally known as the . It operated from Soga Station to
Anegasaki Station in
Ichihara. Several extensions were built over the next few years, and in 1919 it reached Awa-Hōjō (present day
Tateyama). At this time it was renamed the . By 1925 it had been extended to its present-day terminus,
Awa-Kamogawa Station. In 1929, the Hōjō Line was incorporated into the Bōsō Line. However, in 1933, the original section between Soga and Awa-Kamogawa Stations again became its own line, this time renamed the , and in 1972 it received its current name. The Soga - Kimitsu section was duplicated between 1964 and 1971, and the entire line was electrified between 1968 and 1971. Individual section dates as given in the Timeline section below.
Timeline • March 28, 1912 – Kisarazu Line (Soga to Anegasaki) begins operation • August 21, 1912 – Extended from Anegasaki to Kisarazu • January 15, 1915 – Extended from Kisarazu to Kazusa-Minato • October 11, 1916 – Extended from Kazusa-Minato to Hamakanaya • August 1, 1917 – Extended from Hamakanaya to Awa-Katsuyama • August 10, 1918 – Extended from Awa-Katsuyama to Nako-Funakata • May 24, 1919 – Extended from Nako-Funakata to Awa-Hōjō; renamed Hōjō Line • June 1, 1921 – Extended from Awa-Hōjō to Minamihara • December 20, 1922 – Extended from Minamihara to Emi • July 25, 1924 – Extended from Emi to Futomi • July 11, 1925 – Extended from Futomi to Awa-Kamogawa • June 16, 1926 – Takeoka station opened • May 20, 1927 – Chitose railyard opened • August 15, 1929 – Bōsō line extended to Awa-Kamogawa; Hōjō Line incorporated into Bōsō Line • August 1, 1930 – Chitose railyard is upgraded to a station • April 1, 1933 – Bōsō line from Soga to Awa-Kamogawa (the run of the former Hōjō Line) is renamed Bōsō West Line • November 20, 1941 – Iwane station opened • March 1, 1946 – Awa-Hōjō station renamed Tateyama Station • January 10, 1947 – Nagaura station opened • April 10, 1956 – Shūsai station renamed Kimitsu Station • July 1, 1964 – Double-track section built between Soga and Hamano • September 20, 1964 – Double track extended from Hamano to Yawatajuku • July 4, 1965 – Double track extended from Yawatajuku to Goi • May 26, 1968 – Double track extended from Goi to Nagaura • July 13, 1968 – Electric wires extended from Chiba station, past Sogo, extending to Kisarazu • March 20, 1969 – Double track extended from Nagaura to Naraba • July 10, 1969 – 135 C57-105 steam engines removed from service • July 11, 1969 – Electric wires extended from Kisarazu to Chikura • March 18, 1970 – Double track extended from Naraba to Kisarazu • March 24, 1970 – Double track extended from Kisarazu to Kimitsu • July 1, 1971 – Electric wires extended from Chikura to Awa-Kamogawa • July 15, 1972 – Renamed Uchibō Line • March 31, 1974 – Naraba station renamed Sodegaura • November 15, 1982 – Freight service between Kisarazu and Awa-Kamogawa discontinued • April 1, 1987 – Acquired by East Japan Railway Company following the division and privatization of JNR initiated by prime minister
Yasuhiro Nakasone;
Japan Freight Railway Company becomes a second class railway enterprise between Soga and Kisarazu • November 1, 1996 – Japan Freight Railway Company second class enterprise between Soga and Kisarazu is discontinued • February 4, 2001 – ATS-P usage implemented between Chiba and Iwane • October 1, 2009 -
209-2000/2100 series EMUs are introduced on local services • March 13, 2021 -
E131 series EMUs are introduced on local services between Kisarazu and Awa-Kamogawa, replacing most 209-2000/2100 series trains in that section ==References==