From the Wikipedia page 
Hiyama Subprefecture (檜山振興局 Hiyama-shinkō-kyoku) is a subprefecture of Hokkaido Prefecture, Japan located on the Oshima Peninsula on the Sea of Japan side. It includes Okushiri Island. It was established in 1897.
- 1897: Hiyama Subprefecture was established.
- 2005: Kumaishi Town (Nishi District) was merged with Yakumo Town (Yamakoshi District, Oshima Subprefecture) and transferred to Oshima Subprefecture. At the same time, Hiyama Subprefecture was divided between north and south.
- 2014: Esashi Line (from Kikonai Station to Esashi Station) was abolished. Therefore, Hiyama Subprefecture became the only subprefecture in which there is no railway.
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