Monmouth is a city in Jackson County, Iowa, United States.

[6] According to the United States Census Bureau, the city has a total area of 0.56 square miles (1.45 km2), all land.

There were 63 housing units at an average density of 110.8 per square mile (42.8/km2).

There were 69 housing units at an average density of 123.2 per square mile (47.6/km2).

The racial makeup of the city was 98.0% White, 0.7% African American, 0.7% Asian, and 0.7% from two or more races.

27.0% of all households were made up of individuals, and 8% had someone living alone who was 65 years of age or older.

There were 77 housing units at an average density of 137.1 per square mile (52.9/km2).

27.8% of all households were made up of individuals, and 11.1% had someone living alone who was 65 years of age or older.

None of the families and 7.5% of the population were living below the poverty line, including no under eighteens and 12.5% of those over 64.