The ZIP code 21782 in Mercersville, Maryland, has experienced fluctuations in population and population density over the past decade. The population ranged from a low of 3,435 in 2010 to a high of 3,873 in 2013, with the most recent data showing a population of 3,687 in 2022. The population density has varied accordingly, from 109.36 people per square mile in 2010 to 117.38 people per square mile in 2022.

Given the ZIP code's size of 31.41 square miles and the 2022 population density of 117.38 people per square mile, the area can be classified as rural. Rural areas are characterized by larger living spaces, typically ranging from 1 to 5 acres, fewer public services, and lower infrastructure density compared to more urban areas. The lifestyle in rural areas is often community-oriented, centered around local schools and small businesses, with activities such as hobby farming, horse ownership, and significant outdoor activities.

The estimated number of housing units corresponding to the 2022 population, based on the national average household size of 2.61, is approximately 1,413. This suggests that the area is likely composed of single-family homes or small multi-family dwellings, which is consistent with the rural classification.