The Middleton Substation is a 1-story, Italianate building in Middleton, Idaho, that was part of an interurban railway loop that connected Middleton, Boise, Nampa, and Caldwell. Constructed in 1912, the small, 16-ft by 30-ft substation provided space both for transformers and for an office. The Middleton Substation was added to the National Register of Historic Places in 1973, and its nomination included an adjacent generator building constructed in 1907 and later demolished. The site is now home to the Lee Moberly Museum, named after a former Middleton postmaster and local historian.