Dawson is a city in Dallas County, Iowa, United States. The population was 116 at the time of the 2020 census. It is part of the Des Moines–…Dawson is a city in Dallas County, Iowa, United States. The population was 116 at the time of the 2020 census. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area. According to the United States Census Bureau, the city has a total area of 0.48 square miles, all land.