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Where 51240 is
Approximate ZIP boundary (Census ZCTA 2020). ZIP codes are mail routes, not areas, so the shape shown is the Census tabulation area that approximates it.
- 🔢 Type 51240 into a pocket calculator and turn it upside down: OhZIS — not quite a word, sorry.
- ➕ As a number, 51,240 = 2 × 2 × 2 × 3 × 5 × 7 × 61. Its digits add up to 12, a total 940 other ZIP codes share.
- 💾In binary, the way a computer stores it:
1100100000101000 - 🏠 Its numerical neighbours: 51239 (Hull, IA, 17 mi away) and 51241 (Larchwood, IA, 10 mi away).
- 🔄 Backwards, 51240 becomes 04215, which is not a ZIP code at all.
- 👥 73 other ZIP codes are made of exactly the same digits (01245, 01254, 01452, 01524, 01542, 02145, …). The farthest-flung twin is 02541 in Falmouth, MA, 1,318 miles away.
- 🧭 Farther north than 84% of all ZIP codes, and farther west than 72%.
- 🎯264 miles northeast of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 51240 and you would come out at 43.31°S, 83.54°E — 759 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
- ☀Longest day of the year: 15h 24m of daylight. Shortest: 8h 58m.
- 📏 At 100.4 square miles of land, 51240 is bigger than 78% of ZIP codes — room for about 76 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 1,914This ZIP1,914 |
|---|---|
| Households | 632This ZIP632 |
| Housing units | 673This ZIP673 |
| Median age | 34.4This ZIP34.4Iowa38.6US 38.9 |
| Median household income | $83,929This ZIP$83,929Iowa$75,059US $80,734 |
| Median home value | $232,600This ZIP$232,600Iowa$208,000US $332,700 |
| Median gross rent | $993This ZIP$993Iowa$972US $1,413 |
| Bachelor's degree or higher | 16.5%This ZIP16.5% |
| Mean commute | 22.7 minThis ZIP22.7 min |
| Population density | 19.1 / sq miThis ZIP19.1 / sq mi |
Business and tax activity
| Business establishments | 67This ZIP67 |
|---|---|
| Employees | 446This ZIP446 |
| Annual payroll | $14,778,000This ZIP$14,778,000 |
| Tax returns filed | 770This ZIP770 |
| Total adjusted gross income | $71,774,000This ZIP$71,774,000 |
Land area
| Land area | 100.43 sq miThis ZIP100.43 sq mi |
|---|---|
| Water area | 0.11 sq miThis ZIP0.11 sq mi |
Counties 51240 spans
A ZIP code is a mail route and ignores county lines. Shares are by overlapping land area.
| County | Share of this ZIP |
|---|---|
| Lyon County | 85.5% |
| Sioux County | 14.5% |
Other place names in 51240
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 51240
| ZIP | City | Distance |
|---|---|---|
51230 | Alvord, IA | 7.6 mi |
57013 | Canton, SD | 8.6 mi |
57027 | Fairview, SD | 8.7 mi |
51241 | Larchwood, IA | 9.8 mi |
51247 | Rock Valley, IA | 10.0 mi |
51242 | Lester, IA | 10.4 mi |
51235 | Doon, IA | 12.3 mi |
57032 | Harrisburg, SD | 13.6 mi |
57034 | Hudson, SD | 13.7 mi |
57077 | Worthing, SD | 14.8 mi |
Find every ZIP code within 10 miles of 51240 →
Questions about this ZIP code
Where is ZIP code 51240?
51240 is in Inwood, Iowa, in Lyon County. Its published point location is 43.3094, -96.4584.
What county is 51240 in?
51240 spans 2 counties: Lyon County and Sioux County. Most of it falls in Lyon County, measured by overlapping land area — the county holding the most land in a ZIP code is not always the one holding the most residents.
What area code is 51240?
Inwood uses area code 712, from NANPA's telephone records.
What time zone is 51240 in?
51240 uses America/Chicago.
How many people live in 51240?
About 1,914 people live in ZIP code 51240, in 632 households, at 19.1 people per square mile. These are American Community Survey 5-year estimates for the ZIP Code Tabulation Area, not a headcount.
What is the median household income in 51240?
$83,929 a year, against $75,059 across Iowa.
What ZIP codes are near 51240?
The closest are 51230 (7.6 mi), 57013 (8.6 mi), 57027 (8.7 mi), 51241 (9.8 mi) and 51247 (10 mi).
Is 51240 a PO Box ZIP code?
51240 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “51240 ZIP Code — Inwood, Iowa (Lyon County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/51240
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/51240.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.