Alton is a city in Sioux County, Iowa, home to about 1,459 people across 1.9 square miles. Its ZIP code is 51003.
Homes sold for a median of $119 per square foot in the three months ending August 2026, a seller’s market.
Each card is that ZIP code’s whole market, including any part outside Alton. Seller’s market: under 4 months of supply; buyer’s market: over 6. Methodology
We’re writing up Alton’s story and what everyday life there is like, for people thinking about moving in.
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| Nearest major airport | Eppley Airfield (OMA)116 miles away |
|---|---|
| Closer regional airport | Sioux Gateway Airport / Brigadier General Bud Day Field (SUX)44 miles away |
| Nearest city of 250,000+ | Omaha, NE118 miles away |
| Nearest city of 1 million+ | Chicago, IL432 miles away |
Straight-line distances from the center of Alton; driving is longer.
Source: Airports from OurAirports (scheduled passenger service); city centers and populations from the U.S. Census Bureau.
Source: Members of Congress from the congress-legislators project; districts from the Census Bureau’s relationship files; governor and mayor from Wikidata.
Alton had 1,248 residents in the 2020 census, up 14% since 2000.
It’s the 219th largest of 1,019 towns in Iowa by population.
Sioux County grew from 23,337 residents in 1900 to 35,872 in 2020.
Sioux County, 1900–2020
Source: U.S. Census Bureau decennial censuses (counties 1900–1990 from the Bureau’s historical county file).
Average highs peak around 85°F in summer, and winter lows average 9°F. About 30 inches of rain and melted snow fall in a typical year, with about 35 inches of snow.
Source: NOAA 1991–2020 climate normals, Sioux Ctr 2 Se, IA weather station (9 miles away).
20,910 jobs at 1,345 businesses in Sioux County. The biggest industries by employees:
Source: U.S. Census Bureau County Business Patterns 2023 (private employers; jobs counted where people work).
1 doctors and other health care providers list an office in Alton.
Nearest hospitals
Providers with an office here
| Chiropractors | 1 |
|---|
Source: Hospitals from CMS Hospital General Information (ratings are CMS overall star ratings); straight-line distances; providers from the CMS National Plan and Provider Enumeration System (NPPES), by practice address and primary specialty.
Parks (2 nearby)
Grocery stores
Pharmacies
Libraries (1 nearby)
Theaters and performance venues
Counts are within about 1 mile of the center of town.
Source: Map data © OpenStreetMap contributors (openstreetmap.org/copyright), as mapped by volunteers; it can miss places or include closed ones.
Public schools here are run by MOC-Floyd Valley Comm School District. Check each district’s attendance zones for a specific address.
| School | Grades | Students | Type | Distance |
|---|---|---|---|---|
| MOC-Floyd Valley Middle SchoolAlton | 6–8 | 337 | Public | 0.8 mi |
| School | Grades | Students | Affiliation | Distance |
|---|---|---|---|---|
| Spalding Catholic SchoolAlton | Pre-K–6 | 25 | Roman Catholic | 0.7 mi |
| Spalding Catholic SchoolAlton | K–6 | 25 | Roman Catholic | 0.7 mi |
| Spalding Catholic SchoolsAlton | K–6 | 26 | Roman Catholic | 0.7 mi |
Source: U.S. Department of Education, NCES: Common Core of Data (2024-2025) for public schools; Private School Universe Survey (2023-2024) for private schools. Listed by address; we don’t rate schools.
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Town boundaries don’t always match ZIP codes: a ZIP code can cross into neighboring towns, and a town can share a ZIP code with its neighbors. Facts describe the town itself; market figures describe whole ZIP codes.