According to the U.S. Census Bureau, the county has a total area of 641 square miles (1,660 km), of which 638 square miles (1,650 km) is land and 2.8 square miles (7.3 km) (0.4%) is water.
On Sunday, May 22, 2011 Jasper County was struck in Joplin with a catastrophic EF5 multiple-vortex tornado. The 2011 Joplin tornado ranked as the seventh deadliest in America’s history.
As of the census of 2010, there were 117,404 people, 45,639 households, and 30,202 families residing in the county. The population density was 164 people per square mile (63/km²). There were 50,668 housing units at an average density of 71 per square mile (28/km²). The racial makeup of the county was 88.24% White, 1.93% Black or African American, 1.51% Native American, 0.99% Asian, 0.25% Pacific Islander, 3.89% from other races, and 3.18% from two or more races. Approximately 6.84% of the population were Hispanic or Latino of any race.
There were 45,639 households out of which 30.8% had children under the age of 18 living with them, 48.7% were married couples living together, 12.4% had a female householder with no husband present, and 33.8% were non-families. 33.4% of all households were made up of individuals and 24.8% had someone living alone who was 65 years of age or older. The average household size was 2.52 and the average family size was 3.05
In the county, the population was spread out with 27.17% under the age of 19, 7.4% from 20 to 24, 25.11% from 25 to 44, 22.24% from 45 to 64, and 12.14% who were 65 years of age or older. The median age was 35.1 years. For every 100 females, there were 94.10 males. For every 100 females age 18 and over, there were 90.20 males.
The median income for a household in the county was $31,323, and the median income for a family was $37,611. Males had a median income of $28,573 versus $20,386 for females. The per capita income for the county was $16,227. About 10.40% of families and 14.50% of the population were below the poverty line, including 19.20% of those under age 18 and 10.30% of those age 65 or over.