As of the census of 2000, there were 41,165 people, 13,433 households, and 9,953 families residing in the county. The population density was 75 people per square mile (29/km²). There were 15,408 housing units at an average density of 28 per square mile (11/km²). The racial makeup of the county was 78.35% White, 11.99% Black or African American, 1.00% Native American, 2.27% Asian, 0.32% Pacific Islander, 2.50% from other races, and 3.57% from two or more races. 5.84% of the population were Hispanic or Latino of any race.
There were 13,433 households out of which 42.30% had children under the age of 18 living with them, 60.60% were married couples living together, 9.70% had a female householder with no husband present, and 25.90% were non-families. 21.60% of all households were made up of individuals and 7.20% had someone living alone who was 65 years of age or older. The average household size was 2.68 and the average family size was 3.13.
In the county the population was spread out with 27.50% under the age of 18, 16.60% from 18 to 24, 32.00% from 25 to 44, 15.90% from 45 to 64, and 7.90% who were 65 years of age or older. The median age was 28 years. For every 100 females there were 112.10 males. For every 100 females age 18 and over, there were 115.40 males.
The median income for a household in the county was $34,247, and the median income for a family was $37,786. Males had a median income of $26,553 versus $20,500 for females. The per capita income for the county was $14,586. About 8.00% of families and 10.30% of the population were below the poverty line, including 12.40% of those under age 18 and 12.30% of those age 65 or over.
Waynesville Regional Airport at Forney Field serves the community with air service; even though it's on Fort Leonard Wood, it is jointly run by the cities of Waynesville and St. Robert and is available for civilian use by private pilots and scheduled commercial passenger service.
The major east-west route is Interstate 44; before that, the main highway was U.S. Route 66, which still exists as a scenic route through the area and passes through Devil's Elbow, St. Robert, Waynesville, Buckhorn, and Hazelgreen. Names for U.S. Route 66 vary - at different places, it's called Teardrop Road, Highway Z, Old Route 66, Historic Route 66, and Highway 17. State-posted signs mark most of the alignment of the road.
Major north-south routes include:
Major attractions along U.S. Route 66 include the Old Stagecoach Stop in downtown Waynesville, which is now a museum but began as a tavern and boarding house and is the oldest standing structure in the county. It was used as a Civil War hospital for Union troops who were garrisoned above the city in Fort Wayne, which was demolished after the war. The Old Courthouse Museum in downtown Waynesville is near the Old Stagecoach Stop. Three bridges cross the Big Piney River at Devil's Elbow -- the modern Interstate 44 bridge, the later U.S. Route 66 alignment on Highway Z that was made possible by the Hooker Cut through a steep hillside, and the original U.S. Route 66 alignment on Teardrop Road that includes a historic bridge that's in the process of renovation. The Elbow Inn is a biker bar that's a frequent stop the original U.S. Route 66 alignment.