Musselshell County is a county in south-central Montana. As of the 2010 United States Census, the population was 4,538. Its county seat is Roundup.
According to the US Census Bureau, the county has a total area of 1,863.91 square miles (4,827.5 km), of which 1,861.16 square miles (4,820.4 km) is land and 2.75 square miles (7.1 km) (0.1%) is water.
As of the 2000 United States Census there are 4,497 people, 1,878 households, and 1,235 families in the county. The population density is 2 people per square mile (1/km²). There are 2,317 housing units at an average density of <1/km² (1/sq mi). The racial makeup of the county is 96.91% White, 0.07% Black or African American, 1.27% Native American, 0.16% Asian, 0.04% Pacific Islander, 0.38% from other races, and 1.18% from two or more races. 1.60% of the population are Hispanic or Latino of any race. 26.6% were of German, 14.8% English, 8.4% Norwegian, 8.1% Irish and 7.4% American ancestry. 96.5% spoke English and 2.6% German as their first language.
There are 1,878 households out of which 27.20% have children under the age of 18 living with them, 55.60% are married couples living together, 6.60% have a female householder with no husband present, and 34.20% are non-families. 30.10% of all households are made up of individuals and 13.80% have someone living alone who is 65 years of age or older. The average household size is 2.33, and the average family size is 2.91.
The county population contained 23.40% under the age of 18, 5.70% from 18 to 24, 24.00% from 25 to 44, 29.40% from 45 to 64, and 17.50% who are 65 years of age or older. The median age is 43 years. For every 100 females there are 95.40 males. For every 100 females age 18 and over, there are 95.70 males.
The median income for a household in the county is $25,527, and the median income for a family is $32,298. Males have a median income of $25,000 versus $17,813 for females. The per capita income for the county is $15,389. 19.90% of the population and 13.00% of families are below the poverty line. Out of the total population, 31.70% of those under the age of 18 and 10.50% of those 65 and older are living below the poverty line.
As of the 2010 United States Census, there were 4,538 people, 2,046 households, and 1,276 families in the county. The population density was 2.4 inhabitants per square mile (0.93/km). There were 2,654 housing units at an average density of 1.4 per square mile (0.54/km). The racial makeup of the county was 96.1% white, 1.3% American Indian, 0.2% black or African American, 0.2% Asian, 0.2% from other races, and 1.9% from two or more races. Those of Hispanic or Latino origin made up 2.6% of the population. In terms of ancestry, 28.1% were German, 16.5% were English, 16.1% were Irish, 7.6% were Norwegian, and 7.0% were American.
Of the 2,046 households, 23.2% had children under the age of 18 living with them, 52.4% were married couples living together, 6.5% had a female householder with no husband present, 37.6% were non-families, and 33.5% of all households were made up of individuals. The average household size was 2.19 and the average family size was 2.78. The median age was 49.1 years.
The median income for a household in the county was $37,033 and the median income for a family was $47,860. Males had a median income of $33,182 versus $25,750 for females. The per capita income for the county was $20,875. About 14.1% of families and 17.8% of the population were below the poverty line, including 28.6% of those under age 18 and 9.6% of those age 65 or over.