Marshall is a city in Saline County, Missouri, United States.It is the county seat of Saline County,. The Marshall Micropolitan Statistical Area consists of Saline County. It is also home to Missouri Valley College. There were 5,127 housing units at an average density of 505.3 per square mile (195.0/square kilometers). The racial makeup of the city was 86.05% White, 7.40% African American, 0.43% Native American, 0.39% Asian, 0.34% Pacific Islander, 3.46% from other races, and 1.94% from two or more races.