The county is one of the best bellwether regions for voting U.S. presidential elections; it has voted for the winning candidate in every election since 1960 and in all but two elections since 1892. It continued the trend in 2008, voting for Illinois Senator Barack Obama by a 15-point margin.
2000 105,848 1990 106,107 1980 112,385 1970 114,528 1960 108,458 1950 105,160 1940 99,709 1930 98,861 1920 100,212 1910 87,930 1900 62,035 1890 50,195 1880 45,658 1870 33,549 1860 22,517 1850 15,289 1840 12,076 1830 5,766 1820 3,390
As of the census of 2000, there were 105,848 people, 40,998 households, and 26,074 families residing in the county. The population density was 262 people per square mile (101/km²). There were 45,203 housing units at an average density of 112 per square mile (43/km²). The racial makeup of the county was 90.66% White, 6.04% Black or African American, 0.27% Native American, 1.22% Asian, 0.04% Pacific Islander, 0.39% from other races, and 1.38% from two or more races. 1.20% of the population were Hispanic or Latino of any race. 21.6% were of German, 21.0% American, 11.1% English and 9.8% Irish ancestry according to Census 2000.
There were 40,998 households out of which 29.60% had children under the age of 18 living with them, 48.00% were married couples living together, 11.70% had a female householder with no husband present, and 36.40% were non-families. 30.00% of all households were made up of individuals and 11.90% 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 2.96.
In the county the population was spread out with 22.90% under the age of 18, 14.30% from 18 to 24, 27.30% from 25 to 44, 21.30% from 45 to 64, and 14.20% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 96.60 males. For every 100 females age 18 and over, there were 93.80 males.
The median income for a household in the county was $33,184, and the median income for a family was $42,957. Males had a median income of $32,854 versus $22,381 for females. The per capita income for the county was $17,620. About 10.30% of families and 14.10% of the population were below the poverty line, including 17.60% of those under age 18 and 9.50% of those age 65 or over.
The public school district is the Vigo County School Corporation, which at serving over 16,000 students is one of the largest school corporations in the state.