Ulmer is a town in Allendale County, South Carolina, United States. The population was 88 at the 2010 census.
The Williams House was added to the National Register of Historic Places in 1999.
Ulmer is located at 33°5′48″N 81°12′28″W (33.096652, -81.207712).
According to the United States Census Bureau, the town has a total area of 2.7 square miles (7.1 km2), of which 0.012 square miles (0.03 km2), or 0.48%, is water.
As of the census of 2000, there were 102 people, 40 households, and 27 families living in the town. The population density was 103.9 people per square mile (40.2/km2). There were 54 housing units at an average density of 55.0 per square mile (21.3/km2). The racial makeup of the town was 85.29% White, 11.76% African American, 1.96% Native American, and 0.98% from two or more races.
There were 40 households, out of which 32.5% had children under the age of 18 living with them, 60.0% were married couples living together, 2.5% had a female householder with no husband present, and 32.5% were non-families. 27.5% of all households were made up of individuals, and 17.5% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.22.
In the town, the population was spread out, with 31.4% under the age of 18, 2.9% from 18 to 24, 28.4% from 25 to 44, 21.6% from 45 to 64, and 15.7% who were 65 years of age or older. The median age was 38 years.