New Boston is an unincorporated community in central Lee County, Iowa, United States. It lies along U.S. Highway 218 southwest of the city of Fort Madison, the county seat of Lee County. Although New Boston is unincorporated, it has a post office, with the ZIP code of 52619. The community is part of the Fort Madison–Keokuk, IA-MO Micropolitan Statistical Area. There are no commercial establishments in New Boston, although this is the home of the New Boston Mennonite Church.