The area was first settled in 1850, and for a time was known as Union Bench. It started out as an agricultural extension of Springville. Legal action between residents of Springville and what became Mapleton, largely over water rights, allowed Mapleton to chart its own course beginning in 1901 when the community incorporated as a town. Mapleton became a city in 1948.
As of the census of 2000, there were 5,809 people, 1,442 households, and 1,313 families residing in the city. The population density was 629.4 people per square mile (243.0/km²). There were 1,480 housing units at an average density of 160.4 per square mile (61.9/km²). The racial makeup of the city was 97.80% White, 0.14% African American, 0.24% Native American, 0.34% Asian, 0.22% Pacific Islander, 0.52% from other races, and 0.74% from two or more races. Hispanic or Latino of any race were 2.05% of the population.