Anamosa is a city in Jones County, Iowa, United States. The population was 5,450 at the 2020 census. It is the county seat of Jones County. …Anamosa is a city in Jones County, Iowa, United States. The population was 5,450 at the 2020 census. It is the county seat of Jones County. What is now Anamosa was founded as the settlement of Buffalo Forks in 1838 and incorporated as Lexington in 1856. Lexington was a popular name for towns at that time, so when Lexington chose to become incorporated as a city in 1877, the name was changed to Anamosa to avoid mail delivery confusion. There are many stories on how Anamosa was chosen as a name. Some believe it was named for a local Native American girl named Anamosa, meaning "white fawn", while others say it means "You walk with me."