Matsumoto Domain
The area of present-day Ōmachi was part of ancient Shinano Province. The area was part of the holdings of Matsumoto Domain during the Edo period. The modern town of Ōmachi was established with the creation of the municipalities system on April 1, 1889. It merged with the neighboring villages of Taira, Tokiwa and Yashiro on July 1, 1954 to form the city of Ōmachi. On January 1, 2006, the villages of Miasa and Yasaka (both from Kitaazumi District) were merged into Ōmachi.