The Decorah Commercial Historic District is a nationally recognized historic district located in Decorah, Iowa, United States. It was listed on the National Register of Historic Places in 2017. At the time of its nomination it contained 126 resources, which included 85 contributing buildings, one contributing structure, and 40 non-contributing buildings. The historic district covers most of the city's central business district. Water Street, which is a major thoroughfare through the district was named after a millrace (non-extant) that rerouted water from the Upper Iowa River to serve the needs of the mills and the commercial district. The land here is relatively flat and allowed for a linear shopping area. The Broadway–Phelps Park Historic District is largely a residential area that is lo