Fredericksburg is a city in Chickasaw County, Iowa, United States. The population was 987 at the time of the 2020 census. Fredericksburg w…Fredericksburg is a city in Chickasaw County, Iowa, United States. The population was 987 at the time of the 2020 census. Fredericksburg was incorporated on December 18, 1894. The city was named after Frederick Padden, a local settler who platted the village in 1856. In the late 1800s, Dr. William S. Pitts, a local physician and composer who wrote "The Church in the Wildwood", served as mayor of the town.