| ZIP Codes: | 31 ZIP Codes (23 Standard, 7 PO Box, 1 Unique) [See All] |
| Area Codes: | 227 / 240 / 301 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 11:53:46 PM |
| Population: | 299,169 [See All] |
| FIPS: | 24021 |
| CBSA: | Washington-Arlington-Alexandria, DC-VA-MD-WV |
| Land Area: | 639 sq mi |
| Water Area: | 8 sq mi |
| Coordinates: | 39.4409, -77.4053 |
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299,169 residents live across 31 ZIPs covering 639 sq mi, served by 26 distinct USPS-recognized cities.
Population moved from 249,561 to 299,169 from 2014 to 2024 — a +19.9% change. 19 ZIPs gained residents, 8 lost.
The county's wealthiest ZIP 21770 (Monrovia, $183,571 median) and poorest ZIP 21780 (Sabillasville, $83,785) are 25.2 miles apart — a 2.2× income gap across local geography.
Median home values vary 2.0× across this county — from $331,100 in 21727 (Emmitsburg) to $647,300 in 21754 (Ijamsville).
Density varies 22× across the county — from 99 people/sq mi in 21780 (Sabillasville) to 2,166 in 21716 (Brunswick).
Educational attainment ranges from 24.7% bachelor's+ in 21780 (Sabillasville) to 61.6% in 21774 (New Market) — the breadth of educational profiles across the area.
Within Maryland, this is the #7 most populous of 24 counties and ranks #6 for median household income with the #1 fastest decade growth .
On the national stage, Frederick County is ranks #51 for income .
Hosts 1 single-entity Unique ZIP: 21709State Farm Ins Co .
Weighted by population, the typical household earns about $128,748 across the county — reflecting what a typical resident sees, not a simple ZIP average.
46.3% of adults age 25+ hold a bachelor's degree or higher (94,719 of 204,651 reporting).
23 Standard delivery, 7 PO Box only, 1 single-entity Unique ZIPs serve this county.
1 ZIP in this county where more than 60% of adults 25+ hold a bachelor's degree — typically college campuses, research enclaves, or tech corridors.
Frederick County grew 19.9% over the past decade — concentrated in 5 high-growth ZIPs:
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 21702 | Frederick | Standard | 49,605 | $106,983 | 40.9 | 29.8% |
| 21701 | Frederick | Standard | 43,048 | $106,577 | 39.7 | 17.8% |
| 21703 | Frederick | Standard | 41,960 | $106,334 | 32.7 | 27.6% |
| 21771 | Mount Airy | Standard | 33,031 | $157,302 | 88.1 | 11.7% |
| 21704 | Frederick | Standard | 20,006 | $161,063 | 29.3 | 35.0% |
| 21774 | New Market | Standard | 17,134 | $171,103 | 15.6 | 37.9% |
| 21769 | Middletown | Standard | 11,965 | $151,563 | 40.3 | 6.9% |
| 21788 | Thurmont | Standard | 11,654 | $98,856 | 67.9 | -1.2% |
| 21793 | Walkersville | Standard | 10,719 | $121,971 | 21.2 | 5.6% |
| 21770 | Monrovia | Standard | 8,751 | $183,571 | 11.5 | 60.4% |
| 21754 | Ijamsville | Standard | 8,156 | $182,188 | 20.9 | 32.7% |
| 21716 | Brunswick | Standard | 7,200 | $109,382 | 3.3 | 42.9% |
| 21727 | Emmitsburg | Standard | 6,052 | $95,236 | 31.8 | -7.8% |
| 21755 | Jefferson | Standard | 5,909 | $137,417 | 34.9 | -2.2% |
| 21773 | Myersville | Standard | 5,826 | $161,908 | 36.0 | 7.5% |
| 21710 | Adamstown | Standard | 4,661 | $163,864 | 26.8 | -6.7% |
| 21758 | Knoxville | Standard | 4,409 | $111,528 | 32.9 | -7.4% |
| 21798 | Woodsboro | Standard | 2,928 | $116,607 | 16.9 | 10.6% |
| 21777 | Point Of Rocks | Standard | 2,462 | $159,708 | 1.5 | 44.8% |
| 21780 | Sabillasville | Standard | 2,159 | $83,785 | 21.7 | 33.0% |
| 21778 | Rocky Ridge | Standard | 745 | $76,458 | 17.8 | -34.7% |
| 21717 | Buckeystown | PO Box | 245 | $158,413 | 0.2 | 620.6% |
| 21790 | Tuscarora | Standard | 170 | $77,656 | 6.2 | 277.8% |
| 21762 | Libertytown | PO Box | 139 | — | 0.0 | -22.8% |
| 21718 | Burkittsville | Standard | 134 | $93,500 | 0.5 | -12.4% |
| 21714 | Braddock Heights | PO Box | 95 | $161,806 | 0.2 | 82.7% |
| 21705 | Frederick | PO Box | 6 | — | 0.0 | 50.0% |
| 21709 | Frederick | Unique | — | — | 0.0 | — |
| 21792 | Unionville | PO Box | — | — | 0.0 | — |
| 21775 | New Midway | PO Box | — | — | 0.0 | — |
| 21759 | Ladiesburg | PO Box | — | — | 0.0 | — |