Columbia is a town in and the parish seat of Caldwell Parish, Louisiana, United States. The population was 390 as of the 2010 census, down from 477 in 2000.
Columbia is located just east of the center of Caldwell Parish at 32°6′15″N 92°4′37″W / 32.10417°N 92.07694°W / 32.10417; -92.07694 (32.104042, -92.076921), on the southwest bank of the Ouachita River. U.S. Route 165 passes through the center of town and bridges the river, leading north 32 miles (51 km) to Monroe and south 64 miles (103 km) to Alexandria.
According to the United States Census Bureau, the town has a total area of 0.77 square miles (2.00 km), of which 0.76 square miles (1.96 km) is land and 0.01 square miles (0.03 km), or 1.75%, is water.
As of the census of 2000, there were 477 people, 184 households, and 101 families residing in the town. The population density was 629.9 people per square mile (242.3/km²). There were 237 housing units at an average density of 312.9 per square mile (120.4/km²). The racial makeup of the town was 70.02% White, 27.25% African American, 0.63% Native American, 1.47% Asian, 0.42% from other races, and 0.21% from two or more races. Hispanic or Latino of any race were 0.42% of the population.
There were 184 households out of which 21.7% had children under the age of 18 living with them, 40.8% were married couples living together, 12.0% had a female householder with no husband present, and 44.6% were non-families. 41.3% of all households were made up of individuals and 20.1% had someone living alone who was 65 years of age or older. The average household size was 2.23 and the average family size was 3.08.
In the town, the population was spread out with 22.2% under the age of 18, 8.4% from 18 to 24, 26.6% from 25 to 44, 24.5% from 45 to 64, and 18.2% who were 65 years of age or older. The median age was 41 years. For every 100 females, there were 103.8 males. For every 100 females age 18 and over, there were 106.1 males.
The median income for a household in the town was $30,000, and the median income for a family was $33,523. Males had a median income of $33,000 versus $18,000 for females. The per capita income for the town was $13,999. About 19.0% of families and 25.9% of the population were below the poverty line, including 32.0% of those under age 18 and 32.0% of those age 65 or over.