The area around Koshigaya was an inlet of the sea in the
Jōmon period and was settle during the
Yayoi or early
Kofun period. In the Nara period, it was a border area straddling
Musashi and
Shimōsa Provinces. Koshigaya-shuku prospered during the
Edo period as a
post station on the
Nikkō Kaidō and the
Ōshū Kaidō highways, and the town served as the temporary residence of the
Tokugawa shōgun after the 1657
Great Fire of Meireki which destroyed
Edo Castle. The town also had a riverine connection with
Edo and served as a transportation and transshipment center.
Municipal timeline • The town of Koshigaya (then spelled 越ヶ谷) was created within
Minamisaitama District, Saitama with the establishment of the modern municipalities system on April 1, 1889. • It annexed the neighboring villages of Ozawa, Niikata, Sakurai, Obukuro, Ogishima, Dewa, Gamo, Osagami, and Masubayashi on November 3, 1954 and changed the spelling of its name to its present form. • Koshigaya annexed the neighboring village of Soka on November 3, 1955. • Koshigaya was elevated to city status on November 3, 1958. Koshigaya was elevated further to
special city status on April 1, 2003 and to
core city status on April 1, 2015. ==Government==