20851 ZIP Code, Rockville, MD
20851 is a ZIP code in Rockville, Maryland in Montgomery County. It covers 2.5 square miles of land. The closest ZIP codes are 20852, 20853 and 20850. 14,946 people live here in 5,155 households. At about 5,894 people per square mile it is built up to city-neighborhood density, and owners and renters are mixed (57% own). Median household income is $126,411, above the Maryland median of $103,678.
Quick facts
- Mailing city: Rockville, MD
- County: Montgomery County
- Land area: 2.5 sq mi
- Population: 14,946
- Median household income: $126,411
- Carrier routes: 13 (5,051 homes)
Key figures
| Measure | Value |
|---|---|
| Residents | 14,946 |
| Households | 5,155 |
| Median household income | $126,411 |
| Income per person | $51,567 |
| Median age | 38.6 |
| Homeowners | 57.5% |
| Median home value | $568,900 |
| Median rent | $2,043 |
| Bachelor's degree or higher | 46.2% |
| Average commute (minutes) | 31.8 |
| Households with kids under 18 | 32.8% |
| Moved in the past year | 11.2% |
| Below the poverty line | 9.1% |
| Broadband internet | 92.8% |
| Speak a non-English language at home | 56.9% |
Household income
| % of households | Value |
|---|---|
| <$10K | 3.9% |
| $10–15K | 1.2% |
| $15–25K | 2.4% |
| $25–35K | 2.7% |
| $35–50K | 4.0% |
| $50–75K | 13.0% |
| $75–100K | 10.7% |
| $100–150K | 22.7% |
| $150–200K | 16.7% |
| $200K+ | 22.8% |
Age
| % of all residents | Value |
|---|---|
| <10 | 11.0% |
| 10–19 | 10.6% |
| 20–24 | 7.2% |
| 25–34 | 16.5% |
| 35–44 | 12.6% |
| 45–54 | 15.9% |
| 55–64 | 13.2% |
| 65–74 | 8.4% |
| 75+ | 4.7% |
Tenure
| % of housing units | Value |
|---|---|
| Owned, with mortgage | 41.1% |
| Owned outright | 14.9% |
| Rented | 40.6% |
| Vacant | 3.4% |
Type of building
| % of housing units | Value |
|---|---|
| Detached house | 67.0% |
| Townhome | 4.1% |
| 2–4 units | 1.9% |
| 5–19 units | 17.2% |
| 20+ units | 9.6% |
| Mobile / other | 0.0% |
Businesses in 20851
168 business establishments with 1,180 employees (ZIP Codes Business Patterns 2023).
- Construction: 32
- Other Services (except Public Administration): 23
- Retail Trade: 22
- Professional, Scientific, and Technical Services: 20
- Health Care and Social Assistance: 18
- Accommodation and Food Services: 16
- Administrative and Support and Waste Management and Remediation Services: 11
- Real Estate and Rental and Leasing: 6
EDDM carrier routes
20851 has 13 USPS carrier routes with 5,051 residential and 119 business mailboxes. Open the EDDM route map.
Carrier routes in 20851
20851 has 13 USPS carrier routes (13 city (C)) with 5,051 residential and 119 business mailboxes. Routes range from 293 homes (C010) to 630 homes (C012); the median route has 371 homes. The Census counted 5,155 households in 20851 (2020–2024 average); USPS counts current mailboxes, including new and vacant homes.
| Homes per route | Routes |
|---|---|
| 1–249 | 0 |
| 250–499 | 12 |
| 500–749 | 1 |
| 750–999 | 0 |
| 1,000–1,499 | 0 |
| 1,500+ | 0 |
Best routes in 20851 for…
Most businesses
For B2B offers: office supplies, cleaning, IT, catering and commercial services.
- Route C013 — USPS business mailboxes 43, 467 homes
- Route C009 — USPS business mailboxes 26, 332 homes
- Route C001 — USPS business mailboxes 13, 363 homes
- Route C006 — USPS business mailboxes 10, 416 homes
- Route C011 — USPS business mailboxes 8, 444 homes
Select these 5 routes on the route map
Every carrier route in 20851
| Route | Type | Homes | Businesses | Est. median income | Est. owners | Est. families with kids | Est. moved in past year |
|---|---|---|---|---|---|---|---|
| C001 | City | 363 | 13 | $158,970 | — | — | — |
| C002 | City | 371 | 0 | $97,200 | — | — | — |
| C003 | City | 317 | 8 | $155,093 | — | — | — |
| C004 | City | 379 | 2 | $113,168 | — | — | — |
| C006 | City | 416 | 10 | $103,087 | — | — | — |
| C008 | City | 375 | 0 | $128,648 | — | — | — |
| C009 | City | 332 | 26 | $113,168 | — | — | — |
| C010 | City | 293 | 3 | $155,093 | — | — | — |
| C011 | City | 444 | 8 | $131,873 | — | — | — |
| C012 | City | 630 | 3 | $113,168 | — | — | — |
| C013 | City | 467 | 43 | $113,168 | — | — | — |
| C015 | City | 334 | 0 | $116,268 | — | — | — |
| C016 | City | 330 | 3 | $113,168 | — | — | — |
Income, owners, families and movers are estimates for each route (how we estimate them); mailbox counts are current USPS figures. Open 20851 on the EDDM route map.
How route demographics are estimated
Mailbox counts come from USPS; demographics are estimates
The number of homes and businesses on each carrier route is the current USPS EDDM count. The Census Bureau does not publish figures for carrier routes, so income, homeownership, ages, families, movers and housing age on a route are EDDM2GO estimates built from Census block groups (neighborhood areas of roughly 600 to 3,000 people).
How a route gets its figures: the block-group length-share method
We trace each route's streets every 25 meters and record which block group each stretch falls in. The route's homes are spread along its streets in proportion to length, so a route with 60% of its street length in one block group is assumed to have 60% of its homes there. Each block group then contributes its Census counts in proportion to the share of its housing units that sit on the route (capped at the whole block group). Medians are recalculated from the combined income, home-value and age brackets, the way the Census Bureau computes them, not averaged.
Margins of error
Census survey figures carry a margin of error at 90% confidence; we carry it through the calculation and show it as ±. Our margins treat the route-to-block-group split as exact, so the real uncertainty is larger. Routes with fewer than 100 estimated households, large margins, or streets we could not place are flagged.
Different years
USPS mailbox counts are current. Census figures are 5-year averages for 2020–2024, so a new subdivision may have more homes on the route today than the Census counted. Use the route figures to compare routes with each other, not as an exact head count.
Why some routes show identical figures
Two routes that run through the same block group get the same percentages and medians, because the Census publishes one set of figures for the whole block group. Their mailbox counts still differ, and those are exact.
Route and mailbox counts: USPS EDDM route data. Route demographics: EDDM2GO estimates from U.S. Census Bureau American Community Survey 5-year block-group data (2020–2024) and 2024 cartographic block-group boundaries. This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.
Nearby ZIP codes
- 20852 — North Bethesda CDP, MD (1.8 mi)
- 20853 — Aspen Hill CDP, MD (2.2 mi)
- 20850 — Rockville city, MD (3.3 mi)
- 20896 — Garrett Park town, MD (3.3 mi)
- 20906 — Aspen Hill CDP, MD (3.6 mi)
- 20855 — Redland CDP, MD (4.1 mi)
- 20895 — South Kensington CDP, MD (4.2 mi)
- 20902 — Wheaton CDP, MD (4.8 mi)
Areas that include 20851
- Rockville, MD ZIP codes — 4 ZIP codes
- North Bethesda, MD ZIP codes — 6 ZIP codes
- Montgomery County ZIP codes — 48 ZIP codes
- Maryland ZIP code data
Where it ranks
Mail every home in 20851
Route counts on this page price as Full Service 6.5 × 9 postcards: we print, bundle by carrier route and hand the mailing to USPS. Prefer to take it to the Post Office yourself? Print only costs less and you pay postage at drop-off.
EDDM guides
ZIP code statistics describe the Census ZIP Code Tabulation Area (ZCTA) 20851, which approximates the USPS ZIP code area. Census figures: American Community Survey 5-year estimates, 2020–2024.
Frequently asked questions
- What city is 20851 in?
- 20851 is a Rockville, MD mailing address. By land area, 81% lies inside Rockville, 12% lies inside North Bethesda and 7% lies inside Aspen Hill.
- What county is 20851 in?
- 20851 is in Montgomery County.
- What is the population of 20851?
- About 14,946 people (±1,180), according to the Census Bureau's American Community Survey 5-year estimates for 2020–2024. The 2020 Census counted 14,327.
- What is the median household income in 20851?
- $126,411 (±$14,826), compared with $103,678 for Maryland as a whole. Half the households in the ZIP code earn more and half earn less.
- How many carrier routes and mailboxes are in 20851?
- 13 USPS carrier routes with 5,051 residential and 119 business mailboxes (5,170 in all), from the route data stored by EDDM2GO. An EDDM mailing can target any combination of these routes.
- What ZIP codes are near 20851?
- The closest, measured center to center: 20852 (1.8 mi, North Bethesda), 20853 (2.2 mi, Aspen Hill), 20850 (3.3 mi, Rockville), 20896 (3.3 mi, Garrett Park), 20906 (3.6 mi, Aspen Hill) and 20855 (4.1 mi, Redland).
This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.