Ashley is a city in Washington County, Illinois, United States. The population was 536 at the 2010 census. The village was named after …Ashley is a city in Washington County, Illinois, United States. The population was 536 at the 2010 census. The village was named after Colonel L. W. Ashley, a railroad division engineer. According to the 2010 census, Ashley has a total area of 1.122 square miles, of which 1.1 square miles is land and 0.022 square miles is water.