As of 2000, the county population was 49,752. Boyd County is a part of the Huntington-Ashland, WV-KY-OH, Metropolitan Statistical Area (MSA). As of the 2000 census, the MSA had a population of 288,649. .
As of the census of 2000, there were 49,752 people, 20,010 households, and 14,107 families residing in the county. The population density was 311 per square mile (120 /km). There were 21,976 housing units at an average density of 137 per square mile (53 /km). The racial makeup of the county was 95.97% White, 2.55% Black or African American, 0.16% Native American, 0.30% Asian, 0.14% from other races, and 0.88% from two or more races. 1.12% of the population were Hispanic or Latino of any race.
There were 20,010 households out of which 28.90% had children under the age of 18 living with them, 55.70% were married couples living together, 11.60% had a female householder with no husband present, and 29.50% were non-families. 26.50% of all households were made up of individuals and 12.20% had someone living alone who was 65 years of age or older. The average household size was 2.38 and the average family size was 2.86.
The age distribution was 21.80% under the age of 18, 8.30% from 18 to 24, 28.70% from 25 to 44, 25.60% from 45 to 64, and 15.60% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 96.00 males. For every 100 females age 18 and over, there were 93.10 males.
The median income for a household in the county was $32,749, and the median income for a family was $41,125. Males had a median income of $35,728 versus $22,591 for females. The per capita income for the county was $18,212. About 11.50% of families and 15.50% of the population were below the poverty line, including 22.40% of those under age 18 and 12.10% of those age 65 or over.