For statistical purposes, the United States Census Bureau has defined Marion as a census-designated place (CDP).

According to the United States Census Bureau, the CDP has a total area of 1.148 square miles (2.97 km2), all of it land.

There were 99 housing units at an average density of 85.4 per square mile (33.0/km2).

19.6% of all households were made up of individuals, and 13.0% had someone living alone who was 65 years of age or older.

About 38.3% of families and 40.9% of the population were below the poverty line, including 68.5% of those under the age of eighteen and 30.8% of those 65 or over.