The population was 519 at the 2000 census. Northfork was incorporated in 1901, so named because of its location on the north fork of the Elkhorn Creek at its junction with the south fork. It was consolidated with the town of Clark on March 26, 1948.
The town also has a museum which has a variety of coal mining items.
As of the census of 2000, there were 519 people, 229 households, and 130 families residing in the town. The population density was 535.8 inhabitants per square mile (206.9 /km²). There were 298 housing units at an average density of 307.7 per square mile (118.8 /km). The racial makeup of the town was 44.12% White, 53.95% African American, 0.19% Native American, and 1.73% from two or more races. Hispanic or Latino of any race were 0.39% of the population.
There were 229 households out of which 21.8% had children under the age of 18 living with them, 29.3% were married couples living together, 24.9% had a female householder with no husband present, and 42.8% were non-families. 38.9% 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 2.24 and the average family size was 3.03.
In the town the population was spread out with 22.5% under the age of 18, 8.1% from 18 to 24, 22.0% from 25 to 44, 23.3% from 45 to 64, and 24.1% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 79.0 males. For every 100 females age 18 and over, there were 69.6 males.
The median income for a household in the town was $16,544, and the median income for a family was $19,236. Males had a median income of $27,917 versus $20,781 for females. The per capita income for the town was $10,001. About 31.3% of families and 34.4% of the population were below the poverty line, including 52.6% of those under age 18 and 20.9% of those age 65 or over.