• March 16, 1899 - Naka and Tado Districts merged to form Nakatado District. (3 towns, 27 villages)
• April 1, 1899 - The town of Marugame gained city status to become the city of Marugame. (2 towns, 27 villages)
• November 3, 1901 - The villages of Zentsūji, Amino, and Yoshida merged to form the town of Zentsūji. (3 towns, 24 villages)
• June 1, 1917 - The village of Rokugō merged into the city of Marugame. (3 towns, 23 villages)
• May 10, 1942 - The village of Toyohara merged into the town of Tadotsu. (3 towns, 22 villages)
• April 1, 1951 - The village of Minami merged into the city of Marugame. (3 towns, 21 villages)
• April 1, 1953 - The village of Yoshima merged into the city of Sakaide. (3 towns, 20 villages)
• March 31, 1954 (2 towns, 15 villages)
  • The village of Honjima merged into the city of Marugame.
  • The town of Zentsūji and the villages of Yoshiwara, Yogita, Tatsukawa, and Fudeoka merged to form the city of Zentsūji.
• May 3, 1954 - The villages of Shika and Shirakata merged into the town of Tadotsu. (2 towns, 13 villages)
• October 17, 1954 - The village of Gunge merged into the city of Marugame. (2 towns, 12 villages)
• April 1, 1955 (3 towns, 7 villages)
  • The villages of Sogō and Shichika merged to form the village of Chūnan.
  • The town of Kotohira and Enai merged to form the town of Kotohira.
  • The villages of Yoshino, Kanno, and Shijō merged to form the town of Mannō.
• July 1, 1955 - The village of Takashino merged into the town of Mannō. (3 towns, 6 villages)
• 1956年3月31日 - Parts of the town of Mannō merged into the town of Kotohira.
• September 30, 1956 (3 towns, 4 villages)
  • The town of Mannō absorbed the village of Nagasumi, Ayauta District.
  • The villages of Sanagishima and Takamishima merged into the town of Tadotsu.
• October 10, 1957 - Parts of the town of Mannō merged into the town of Kotohira.
• November 1, 1957 - The village of Kotonami, Ayauta District moved to Nakatado District. (3 towns, 5 villages)
• March 31, 1958 - The village of Zōgō split and merged into the town of Kotohira and the city of Zentsūji. (3 towns, 4 villages)
• May 1, 1958 - The villages of Tarumi and Hiroshima merged into the city of Marugame. (3 towns, 2 villages)
• April 1, 1962 - The village of Kotonami gained town status to become the town of Kotonami. (4 towns, 1 village)
• January 1, 1970 - The village of Chūnan gained town status to become the town of Chūnan. (5 towns)
• March 20, 2006 - The towns of Mannō (満濃町) absorbed the towns of Chūnan and Kotonami to form the new town of Mannō (まんのう町). (3 towns)

34°11′31″N 133°50′20″E / 34.192°N 133.839°E / 34.192; 133.839