Canby is a city in Clackamas County, Oregon, United States. The population was 18,171 at the 2020 census. It is along Oregon Route …Canby is a city in Clackamas County, Oregon, United States. The population was 18,171 at the 2020 census. It is along Oregon Route 99E, 2 miles northeast of Barlow. Canby is named for Edward Richard Sprigg Canby, a Civil War general who was later killed in the Modoc War by Captain Jack and his group of warriors.