40121 ZIP Code, Fort Knox, KY
40121 is a ZIP code in Fort Knox, Kentucky — mostly in Hardin County (84% of its land), with smaller parts in Meade County. It covers 35 square miles of land. The closest ZIP codes are 40155, 40177 and 40160. 8,836 people live here in 2,226 households. With about 251 people per square mile it is lightly settled, and most households rent (0% own). Median household income is $82,663, above the Kentucky median of $63,726; 61% of households have children under 18.
Quick facts
- Mailing city: Fort Knox, KY
- County: Hardin County
- Land area: 35 sq mi
- Population: 8,836
- Median household income: $82,663
- Carrier routes: 5 (2,757 homes)
Key figures
| Measure | Value |
|---|---|
| Residents | 8,836 |
| Households | 2,226 |
| Median household income | $82,663 |
| Income per person | $32,370 |
| Median age | 24 |
| Homeowners | 0.0% |
| Median home value | not published |
| Median rent | $1,502 |
| Bachelor's degree or higher | 48.3% |
| Average commute (minutes) | 12.4 |
| Households with kids under 18 | 61.1% |
| Moved in the past year | 34.3% |
| Below the poverty line | 9.0% |
| Broadband internet | 96.6% |
| Speak a non-English language at home | 16.3% |
Household income
| % of households | Value |
|---|---|
| <$10K | 2.1% |
| $10–15K | 1.6% |
| $15–25K | 6.6% |
| $25–35K | 1.9% |
| $35–50K | 7.7% |
| $50–75K | 25.7% |
| $75–100K | 12.2% |
| $100–150K | 22.6% |
| $150–200K | 12.1% |
| $200K+ | 7.4% |
Age
| % of all residents | Value |
|---|---|
| <10 | 23.1% |
| 10–19 | 14.2% |
| 20–24 | 14.0% |
| 25–34 | 20.1% |
| 35–44 | 19.7% |
| 45–54 | 5.6% |
| 55–64 | 1.5% |
| 65–74 | 0.8% |
| 75+ | 1.0% |
Tenure
| % of housing units | Value |
|---|---|
| Owned, with mortgage | 0.0% |
| Owned outright | 0.0% |
| Rented | 89.1% |
| Vacant | 10.9% |
Type of building
| % of housing units | Value |
|---|---|
| Detached house | 23.2% |
| Townhome | 46.9% |
| 2–4 units | 13.5% |
| 5–19 units | 8.1% |
| 20+ units | 8.0% |
| Mobile / other | 0.1% |
Businesses in 40121
55 business establishments with 1,015 employees (ZIP Codes Business Patterns 2023).
- Professional, Scientific, and Technical Services: 14
- Administrative and Support and Waste Management and Remediation Services: 9
- Accommodation and Food Services: 6
- Other Services (except Public Administration): 6
- Retail Trade: 5
- Finance and Insurance: 4
- Health Care and Social Assistance: 4
EDDM carrier routes
40121 has 5 USPS carrier routes with 2,757 residential and 11 business mailboxes. Open the EDDM route map.
Carrier routes in 40121
40121 has 5 USPS carrier routes (5 city (C)) with 2,757 residential and 11 business mailboxes. Routes range from 491 homes (C001) to 625 homes (C008); the median route has 541 homes. The Census counted 2,226 households in 40121 (2020–2024 average); USPS counts current mailboxes, including new and vacant homes.
| Homes per route | Routes |
|---|---|
| 1–249 | 0 |
| 250–499 | 2 |
| 500–749 | 3 |
| 750–999 | 0 |
| 1,000–1,499 | 0 |
| 1,500+ | 0 |
Best routes in 40121 for…
Most businesses
For B2B offers: office supplies, cleaning, IT, catering and commercial services.
- Route C001 — USPS business mailboxes 7, 491 homes
- Route C009 — USPS business mailboxes 3, 607 homes
- Route C005 — USPS business mailboxes 1, 541 homes
Select these 3 routes on the route map
Every carrier route in 40121
| Route | Type | Homes | Businesses | Est. median income | Est. owners | Est. families with kids | Est. moved in past year |
|---|---|---|---|---|---|---|---|
| C001 | City | 491 | 7 | $58,469 | — | — | — |
| C005 | City | 541 | 1 | $103,809 | — | — | — |
| C008 | City | 625 | 0 | $65,739 | — | — | — |
| C009 | City | 607 | 3 | $100,387 | — | — | — |
| C010 | City | 493 | 0 | $58,469 | — | — | — |
Income, owners, families and movers are estimates for each route (how we estimate them); mailbox counts are current USPS figures. Open 40121 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
- 40155 — Muldraugh city, KY (2.4 mi)
- 40177 — West Point city, KY (5.6 mi)
- 40160 — Radcliff city, KY (8 mi)
- 40117 — Ekron city, KY (9.2 mi)
- 40175 — Vine Grove city, KY (10.3 mi)
- 47135 — Laconia town, IN (10.5 mi)
- 40108 — Brandenburg city, KY (12 mi)
- 40272 — Louisville/Jefferson County metro government (balance), KY (12 mi)
Areas that include 40121
- Fort Knox, KY ZIP codes — 1 ZIP code
- Hardin County ZIP codes — 13 ZIP codes
- Meade County ZIP codes — 10 ZIP codes
- Kentucky ZIP code data
Where it ranks
- No. 3 of 12: highest median household income in Hardin County
- No. 1 of 12: highest share of households with children in Hardin County
- No. 1 of 12: highest share of residents who moved in during the past year in Hardin County
- No. 1 of 12: lowest median age in Hardin County
Mail every home in 40121
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) 40121, which approximates the USPS ZIP code area. Census figures: American Community Survey 5-year estimates, 2020–2024.
Frequently asked questions
- What city is 40121 in?
- 40121 is a Fort Knox, KY mailing address. By land area, 42% lies inside Fort Knox; the rest is outside any Census-defined city or community.
- What county is 40121 in?
- 40121 is mostly in Hardin County (84% of its land), with smaller parts in Meade County.
- What is the population of 40121?
- About 8,836 people (±787), according to the Census Bureau's American Community Survey 5-year estimates for 2020–2024. The 2020 Census counted 7,749.
- What is the median household income in 40121?
- $82,663 (±$14,292), compared with $63,726 for Kentucky as a whole. Half the households in the ZIP code earn more and half earn less.
- How many carrier routes and mailboxes are in 40121?
- 5 USPS carrier routes with 2,757 residential and 11 business mailboxes (2,768 in all), from the route data stored by EDDM2GO. An EDDM mailing can target any combination of these routes.
- What ZIP codes are near 40121?
- The closest, measured center to center: 40155 (2.4 mi, Muldraugh), 40177 (5.6 mi, West Point), 40160 (8 mi, Radcliff), 40117 (9.2 mi, Ekron), 40175 (10.3 mi, Vine Grove) and 47135 (10.5 mi, Laconia).
This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.