Peter Johnston was a member of the Wisconsin State Assembly.
Johnston was a member of the Assembly during the 1877 session. From 1870 to 1872, he was Mayor of Manitowoc. Additionally, Johnston was a member of the Manitowoc City Council and of the Manitowoc County, Wisconsin Board of Supervisors. He was a Republican.
- R. M. Bashford, ed. (1877). The Legislative Manual of the State of Wisconsin (16th ed.). Madison: R. B. Bolens. p. 466.
- Lawrence S. Barish, ed. (2007). State of Wisconsin Blue Book 2007 - 2008 (PDF). Madison: Wisconsin Legislature Joint Committee on Legislative Organization. p. 150.
- "History of the Mayor". City of Manitowoc. Retrieved 2015-11-30.