Montgomery County is a county in the east central part of the U.S. state of Missouri. As of the 2010 census, the population was 12,236. Its county seat is Montgomery City. The county was named in honor of Richard Montgomery, an American Revolutionary War general killed in 1775 while attempting to capture Quebec City, Canada.
According to the U.S. Census Bureau, the county has a total area of 542 square miles (1,400 km), of which 536 square miles (1,390 km) is land and 5.8 square miles (15 km) (1.1%) is water.
As of the census of 2000, there were 12,136 people, 4,775 households, and 3,337 families residing in the county. The population density was 23 people per square mile (9/km²). There were 5,726 housing units at an average density of 11 per square mile (4/km²). The racial makeup of the county was 95.97% White, 2.04% Black or African American, 0.24% Native American, 0.26% Asian, 0.01% Pacific Islander, 0.21% from other races, and 1.28% from two or more races. Approximately 0.77% of the population were Hispanic or Latino of any race. 39.1% were of German, 18.4% American, 10.2% English and 9.2% Irish ancestry.
There were 4,775 households out of which 31.30% had children under the age of 18 living with them, 56.90% were married couples living together, 8.60% had a female householder with no husband present, and 30.10% were non-families. 26.30% of all households were made up of individuals and 13.20% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 2.97.
In the county, the population was spread out with 25.40% under the age of 18, 7.40% from 18 to 24, 26.10% from 25 to 44, 23.90% from 45 to 64, and 17.20% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 98.10 males. For every 100 females age 18 and over, there were 93.70 males.
The median income for a household in the county was $32,772, and the median income for a family was $38,632. Males had a median income of $27,933 versus $19,809 for females. The per capita income for the county was $15,092. About 8.40% of families and 11.80% of the population were below the poverty line, including 15.60% of those under age 18 and 10.60% of those age 65 or over.