As of 2003, the village had an estimated population of 4,814 and a population density of 151.10 persons per km2. The total area was 31.86 km2.
On January 1, 2006, Washima, along with the city of Tochio, and the towns of Teradomari and Yoita (all from Santō District), was merged into the expanded city of Nagaoka.[1][2]
^"市町村合併に伴う町名変更一覧". Nagaoka City (in Japanese). Retrieved 2024-02-04.
^住民基本台帳人口移動報告年報 [Annual Report on Population Movement in the Basic Resident Register] (in Japanese). 総務庁統計局. 2006. p. 135. Tochio-shi, Washima‐mura, Teradomari‐machi and Yoita‐machi were incorporated into Nagaoka-shi as of January 1, 2006.