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Where 51003 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 51003 into a pocket calculator and turn it upside down: EOOIS — not quite a word, sorry.
- ➕ As a number, 51,003 = 3 × 3 × 3 × 1889. Its digits add up to 9, a total 375 other ZIP codes share.
- 💾In binary, the way a computer stores it:
1100011100111011 - 🏠 Its numerical neighbours: 51002 (Alta, IA, 39 mi away) and 51004 (Anthon, IA, 42 mi away).
- 🔄 Backwards, 51003 becomes 30015 — and that is a real ZIP code: Covington, GA, 922 miles away.
- 👥 31 other ZIP codes are made of exactly the same digits (01035, 01053, 01350, 01503, 03051, 03105, …). The farthest-flung twin is 03051 in Hudson, NH, 1,240 miles away.
- 🧭 Farther north than 82% of all ZIP codes, and farther west than 71%.
- 🎯256 miles northeast of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 51003 and you would come out at 42.99°S, 84.01°E — 791 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
- ☀Longest day of the year: 15h 22m of daylight. Shortest: 9h 00m.
- 📏 At 54.3 square miles of land, 51003 is bigger than 62% of ZIP codes — room for about 41 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 1,938This ZIP1,938 |
|---|---|
| Households | 730This ZIP730 |
| Housing units | 788This ZIP788 |
| Median age | 37.1This ZIP37.1Iowa38.6US 38.9 |
| Median household income | $101,250This ZIP$101,250Iowa$75,059US $80,734 |
| Median home value | $232,700This ZIP$232,700Iowa$208,000US $332,700 |
| Median gross rent | $813This ZIP$813Iowa$972US $1,413 |
| Bachelor's degree or higher | 29.2%This ZIP29.2% |
| Mean commute | 21.1 minThis ZIP21.1 min |
| Population density | 35.7 / sq miThis ZIP35.7 / sq mi |
Business and tax activity
| Business establishments | 44This ZIP44 |
|---|---|
| Employees | 175This ZIP175 |
| Annual payroll | $7,882,000This ZIP$7,882,000 |
| Tax returns filed | 740This ZIP740 |
| Total adjusted gross income | $61,731,000This ZIP$61,731,000 |
Land area
| Land area | 54.35 sq miThis ZIP54.35 sq mi |
|---|---|
| Water area | 0.03 sq miThis ZIP0.03 sq mi |
Other place names in 51003
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 51003
| ZIP | City | Distance |
|---|---|---|
51041 | Orange City, IA | 5.2 mi |
51022 | Granville, IA | 7.1 mi |
51238 | Hospers, IA | 7.5 mi |
51036 | Maurice, IA | 10.4 mi |
51045 | Oyens, IA | 12.3 mi |
51250 | Sioux Center, IA | 13.1 mi |
51050 | Remsen, IA | 13.2 mi |
51234 | Boyden, IA | 14.1 mi |
51201 | Sheldon, IA | 14.6 mi |
51231 | Archer, IA | 14.7 mi |
Find every ZIP code within 10 miles of 51003 →
Questions about this ZIP code
Where is ZIP code 51003?
51003 is in Alton, Iowa, in Sioux County. Its published point location is 42.9896, -95.9860.
What county is 51003 in?
51003 lies in Sioux County.
What area code is 51003?
Alton uses area code 712, from NANPA's telephone records.
What time zone is 51003 in?
51003 uses America/Chicago.
How many people live in 51003?
About 1,938 people live in ZIP code 51003, in 730 households, at 35.7 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 51003?
$101,250 a year, against $75,059 across Iowa.
What ZIP codes are near 51003?
The closest are 51041 (5.2 mi), 51022 (7.1 mi), 51238 (7.5 mi), 51036 (10.4 mi) and 51045 (12.3 mi).
Is 51003 a PO Box ZIP code?
51003 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “51003 ZIP Code — Alton, Iowa (Sioux County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/51003
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/51003.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.