Mt. Lebanon was probably the first permanent settlement in what is now Bienville Parish. Its pioneers were Baptists from South Carolina who quickly established a church and school. The school became Mount Lebanon University in 1853, but closed during the Civil War to serve as a high school and a confederate hospital. After the war the school was moved to Pineville, Louisiana and became Louisiana College.
The Mt. Lebanon Baptist Church was organized in 1837, and the Louisiana Southern Baptist Convention was established there that year. The church building is still in use. The sanctuary is separated down the middle, men would sit on one side of the divide, women on the other. There is a balcony where the slaves were seated.
There are eight houses in the town that are on the National Register of Historic Places, including a building once used as a stage coach stop and hotel.
After the railroad was built through Gibsland, Louisiana, three miles north, Mt. Lebanon began to decline in population and economic opportunity. The post office there was decommissioned in the 1950s.
As of the census of 2000, there are 73 people, 34 households, and 21 families residing in the town. The population density is 7.0/km² (18.1/mi²). There are 44 housing units at an average density of 4.2/km² (10.9/mi²). The racial makeup of the town is 76.71% White, 23.29% African American, 0.00% Native American, 0.00% Asian, 0.00% Pacific Islander, 0.00% from other races, and 0.00% from two or more races. 0.00% of the population are Hispanic or Latino of any race.
There are 34 households out of which 23.5% have children under the age of 18 living with them, 44.1% are married couples living together, 14.7% have a female householder with no husband present, and 38.2% are non-families. 35.3% of all households are made up of individuals and 20.6% have someone living alone who is 65 years of age or older. The average household size is 2.15 and the average family size is 2.76.
In the town the population is spread out with 17.8% under the age of 18, 0.0% from 18 to 24, 27.4% from 25 to 44, 19.2% from 45 to 64, and 35.6% who are 65 years of age or older. The median age is 48 years. For every 100 females there are 82.5 males. For every 100 females age 18 and over, there are 93.5 males.
The median income for a household in the town is $46,250, and the median income for a family is $54,375. Males have a median income of $32,500 versus $30,417 for females. The per capita income for the town is $18,219. 13.8% of the population and 10.5% of families are below the poverty line. Out of the total people living in poverty, 0.0% are under the age of 18 and 25.0% are 65 or older.