Middletown is a city in Des Moines County, Iowa, United States. The population was 318 at the 2010 census. It is part of the Burlington, IA–IL Micropolitan Statistical Area.
Middletown was laid out in 1846.
Middletown is located at 40°49′41″N 91°15′37″W (40.827925, -91.260347).
According to the United States Census Bureau, the city has a total area of 0.61 square miles (1.58 km2), all land.
At the 2010 census there were 318 people in 127 households, including 94 families, in the city. The population density was 521.3 inhabitants per square mile (201.3/km2). There were 148 housing units at an average density of 242.6 per square mile (93.7/km2). The racial makup of the city was 95.3% White, 1.6% African American, 1.6% Asian, 0.9% Pacific Islander, and 0.6% from two or more races. Hispanic or Latino of any race were 1.3%.
Of the 127 households 34.6% had children under the age of 18 living with them, 58.3% were married couples living together, 9.4% had a female householder with no husband present, 6.3% had a male householder with no wife present, and 26.0% were non-families. 22.8% of households were one person and 7.8% were one person aged 65 or older. The average household size was 2.50 and the average family size was 2.88.