The Downtown Cohoes Historic District takes up 35 acres (14 ha) of the city of Cohoes, New York, United States. Many of the 165 contributing properties date from the 1820-1930 period when the Erie Canal and Harmony Mills were the mainstay of the city's economy. It was recognized as a historic district and added to the National Register of Historic Places in 1984. After years of neglect and decline, it has recently started to see an upswing in business activity due to its historic character and the city's efforts to protect it.