Marceline is made up of a population of 2,123 according to the 2020 census. It is located in North Central Missouri, 39.6943 N (Latitude) and -92.9287 W (Longitude), and it is made up of an area of 3.5 square miles. There are two counties that make up Marceline which are Linn & Chariton counties; it is also the second largest city of Linn County.

The population is spread out with 26.7% under the age of 18 living with them, 48.8% were married couples living together, 11.4% had a female householder with no husband, and 36.0 % were made up of non-families. 32.4 % of all households were made up of individuals and 17.6% were living alone over the age of 65 years old. The average household size was 2.32 and the average family size was 2.95.

The median income for a household in the city was $25,164 and the median income for a family $35,948. About 9.0% of families and 13.1% of the population were below the poverty line, including 15.3% of those under the age of 18 and 19.5% over the age of 65.