Mississippi Mills is a town in eastern Ontario, Canada, in Lanark County on the Mississippi River. It is made up of the former Townships of Ramsay and Pakenham, as well as the Town of Almonte. It is partly located within Canada's National Capital Region.

Lanark County is a county located in the Canadian province of Ontario. Its county seat is Perth, which was first settled in 1816 and was known as a social and political capital before being over shadowed by what we now know as Ottawa.