On May 24, 1919, the line's name changed to the Hōjō Line, and on April 15, 1929 to the Bōsō Line and on April 1, 1933 to the Bōsōnishi Line. It became part of the Japan National Railways (JNR) after World War II, and the line was renamed the Uchibō Line from July 15, 1972.
The line's name changed from Hōjō to Bōsō on May 24, 1919; then to Bōsōnishi on April 15, 1929; and later to Uchibō on July 15, 1972. The line was under Japan National Railways (JNR) after World War II.