|U.S. Decennial Census|
From a peak of population in 1910, the county had declined through 1990. In the early part of the 20th century, particularly from 1910 to 1930, and from 1940 to 1970, it was affected by the Great Migration of blacks out of the segregated society for jobs and opportunities in Midwest and later, West Coast cities. From 1910 to 1920, the population declined more than 17%, as may be seen from the Census table at right. Particularly in the early 20th century, Blacks left to escape the oppression and violence associated with Jim Crow, lynchings, and their disenfranchisement after 1890.
From 1940 to 1960, the population declined by more than 29%. Rural whites also left in those years, but a much greater number of African Americans migrated to other areas. After 1930 they became a minority in the county. In 2000, they constituted nearly 43% of the population.
As of the 2010 United States Census, there were 13,131 people living in the county. 57.7% were White, 41.3% Black or African American, 0.2% Native American, 0.1% Asian, 0.2% of some other race and 0.6% of two or more races. 0.8% were Hispanic or Latino (of any race).
As of the census of 2000, there were 13,599 people, 5,271 households, and 3,879 families living in the county. The population density was 19 people per square mile (7/km2). There were 6,446 housing units at an average density of 9 per square mile (3/km2). The racial makeup of the county was 56.42% White, 42.65% Black or African American, 0.13% Native American, 0.08% Asian, 0.01% Pacific Islander, 0.21% from other races, and 0.49% from two or more races. 0.83% of the population were Hispanic or Latino of any race.
There were 5,271 households out of which 31.20% had children under the age of 18 living with them, 53.10% were married couples living together, 16.30% had a female householder with no husband present, and 26.40% were non-families. 24.50% of all households were made up of individuals and 12.00% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.06.
In the county, the population was spread out with 26.00% under the age of 18, 8.50% from 18 to 24, 25.60% from 25 to 44, 24.60% from 45 to 64, and 15.30% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 93.30 males. For every 100 females age 18 and over, there were 89.80 males.
The median income for a household in the county was $26,033, and the median income for a family was $31,256. Males had a median income of $28,306 versus $16,173 for females. The per capita income for the county was $14,048. About 19.30% of families and 22.60% of the population were below the poverty line, including 29.70% of those under age 18 and 22.20% of those age 65 or over.
- Centreville (mostly in Wilkinson County)
- Crosby (partly in Wilkinson County)
- Liberty (county seat)
Political affiliation and voting patterns in federal elections generally follow those of other traditional southern states, where strong affiliation of conservative whites to the Democratic Party dominated during the period up to and just beyond the Civil Rights era of the 1960s and 1970s. With the rise of the Republican Party of Richard Nixon and Ronald Reagan, the white population gradually began to support Republican national candidates, and ultimately shifted into the party. Given the support of the national Democratic Party leaders through the civil rights years, African-American voters affiliated with that party.
In several elections between World War II and the Civil Rights period, in a period of increasing social change, the white people of Amite County (who were the only ones able to vote in that period) voted for third party candidates, including Dixiecrat candidate Strom Thurmond in 1948 (after Democrat President Harry S. Truman had taken action that year to integrate the military), Harry F. Byrd in 1960, and segregationist George Wallace in 1968.