Saint John Plantation was organized for election purposes in 1859, 1860, and 1868, for tax purposes in 1871, and for general purposes on June 17, 1874, according to the State Archives; although the sign that the locality has erected states that it was established in 1870.
With the Saint John River forming the plantation's northern boundary, Saint John Plantation can be reached by Maine Route 161, a dead end road that leads west from Fort Kent to serve the small communities along the river.