Doniphan is a city in Ripley County, Missouri, United States. The population was 1,997 at the 2010 census. It is the county seat of Ripley County.
The first settlement at Doniphan was made in the 1840s. The community was named for Alexander William Doniphan. A post office called Doniphan has been in operation since 1848.
As of 1900, Doniphan was a sundown town that prohibited African Americans from living there.
Doniphan is located at 36°37′20″N 90°49′20″W (36.622106, -90.822179). According to the United States Census Bureau, the city has a total area of 1.38 square miles (3.57 km2), all land.
As of the census of 2010, there were 1,997 people, 852 households, and 485 families living in the city. The population density was 1,447.1 inhabitants per square mile (558.7/km2). There were 966 housing units at an average density of 700.0 per square mile (270.3/km2). The racial makeup of the city was 96.64% White, 0.15% Black or African American, 0.55% Native American, 0.80% Asian, 0.80% from other races, and 1.05% from two or more races. Hispanic or Latino of any race were 1.70% of the population.