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Where 81101 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 81101 into a pocket calculator and turn it upside down: IOIIB — not quite a word, sorry.
- ➕ 81101 is a prime number. It cannot be divided by anything except 1 and itself. Its digits add up to 11, a total 714 other ZIP codes share.
- 💾In binary, the way a computer stores it:
10011110011001101 - 🏠 Its numerical neighbours: 81092 (Wiley, CO, 169 mi away) and 81102 (Alamosa, CO, 2 mi away).
- 🔄 Backwards, 81101 becomes 10118 — and that is a real ZIP code: New York, NY, 1,714 miles away.
- 👥 7 other ZIP codes are made of exactly the same digits (01118, 10118, 11801, 18011, 18101, 80111, …). The farthest-flung twin is 01118 in Springfield, MA, 1,787 miles away.
- 🧭 Farther south than 62% of all ZIP codes, and farther west than 83%.
- 🎯425 miles west of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 81101 and you would come out at 37.47°S, 74.15°E — 844 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
- ☀Longest day of the year: 14h 45m of daylight. Shortest: 9h 34m.
- 📏 At 369.0 square miles of land, 81101 is bigger than 96% of ZIP codes — room for about 280 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 15,550This ZIP15,550 |
|---|---|
| Households | 6,292This ZIP6,292 |
| Housing units | 6,812This ZIP6,812 |
| Median age | 33.4This ZIP33.4Colorado37.7US 38.9 |
| Median household income | $54,844This ZIP$54,844Colorado$95,470US $80,734 |
| Median home value | $240,400This ZIP$240,400Colorado$539,400US $332,700 |
| Median gross rent | $912This ZIP$912Colorado$1,761US $1,413 |
| Bachelor's degree or higher | 32.4%This ZIP32.4% |
| Mean commute | 15.9 minThis ZIP15.9 min |
| Population density | 42.1 / sq miThis ZIP42.1 / sq mi |
Business and tax activity
| Business establishments | 465This ZIP465 |
|---|---|
| Employees | 5,760This ZIP5,760 |
| Annual payroll | $272,213,000This ZIP$272,213,000 |
| Tax returns filed | 6,800This ZIP6,800 |
| Total adjusted gross income | $401,406,000This ZIP$401,406,000 |
Land area
| Land area | 369.00 sq miThis ZIP369.00 sq mi |
|---|---|
| Water area | 0.54 sq miThis ZIP0.54 sq mi |
Counties 81101 spans
A ZIP code is a mail route and ignores county lines. Shares are by overlapping land area.
| County | Share of this ZIP |
|---|---|
| Alamosa County | 94.4% |
| Conejos County | 5.6% |
Other place names in 81101
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 81101
| ZIP | City | Distance |
|---|---|---|
81102 | Alamosa, CO | 1.7 mi |
81135 | Homelake, CO | 15.3 mi |
81146 | Mosca, CO | 15.9 mi |
81123 | Blanca, CO | 16.2 mi |
81144 | Monte Vista, CO | 16.8 mi |
81136 | Hooper, CO | 17.4 mi |
81151 | Sanford, CO | 17.7 mi |
81124 | Capulin, CO | 18.9 mi |
81140 | La Jara, CO | 20.6 mi |
81141 | Manassa, CO | 21.4 mi |
Find every ZIP code within 10 miles of 81101 →
Questions about this ZIP code
Where is ZIP code 81101?
81101 is in Alamosa, Colorado, in Alamosa County, part of the Alamosa, CO micropolitan area. Its published point location is 37.4693, -105.8527.
What county is 81101 in?
81101 spans 2 counties: Alamosa County and Conejos County. Most of it falls in Alamosa 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 81101?
Alamosa uses area code 719, from NANPA's telephone records.
What time zone is 81101 in?
81101 uses America/Denver.
How many people live in 81101?
About 15,550 people live in ZIP code 81101, in 6,292 households, at 42.1 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 81101?
$54,844 a year, against $95,470 across Colorado.
What ZIP codes are near 81101?
The closest are 81102 (1.7 mi), 81135 (15.3 mi), 81146 (15.9 mi), 81123 (16.2 mi) and 81144 (16.8 mi).
Is 81101 a PO Box ZIP code?
81101 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “81101 ZIP Code — Alamosa, Colorado (Alamosa County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/81101
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/81101.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.