Zip Code 21655 — Preston, MD
21655 is a ZIP Code associated with Preston, MD, located within Caroline. 21655 ranks #3 out of 8 ZIP codes in Caroline County by population (and #239 out of 477 in MD). The area supports an estimated population of 5,053 residents across Data Pending housing units, with a population density of 37.0 people per square mile.
WorldPlaceData database updated: October 2026
📍 View location on OpenStreetMap (38.746010, -75.921030)
| Data Metric | Local Statistic |
|---|
| Postal / Zip Code | 21655 |
| Primary City | Preston |
| State / Province | MD |
| County | Caroline |
| Total Population | 5,053 |
| Median Household Income | Data Pending |
| Total Housing Units | Data Pending |
| Population Density | 37.0 people/sq mi |
| Timezone | America/New_York |
How 21655 Compares
| Metric | ZIP 21655 | Caroline County | MD State Average |
|---|
| Population | 5,053 | 32,942 (Total) | 6,205,597 (Total) |
| Average ZIP Income | Data Pending | N/A | N/A |
| Population Density | 37.0 /sq mi | -- | -- |
| County Pop Rank | #3 of 8 | -- | -- |
Nearby ZIP Codes
Data Sources & Methodology: Geographic coordinates and ZIP Code assignments are derived from underlying geographic and postal datasets. Note that ZIP Codes are USPS postal delivery areas, while Census ZCTAs are statistical approximation areas. Read full methodology →