De Witt is a city located in the U.S. state of Iowa. It is within and the fastest growing city in Clinton County. It has a total area of 5.98 square miles at 41°49′22″N 90°32′34″W. The elevation is 709 feet above sea level. As of the 2010 census data, it had a total population of 5,322. The population density was 890/sq mi. It has Zip code 52742.