Oldest ZIP codes in Pottawattamie County, IA
These are the 14 ZIP codes in Pottawattamie County with the highest median age, out of 14 with at least 1,000 residents. 51577 (Walnut, 64.9), 51535 (Griswold, 50.4) and 51575 (Treynor, 48.1) lead the list. There is no single "best" ZIP code in Pottawattamie County; the right one depends on who you want to reach, so the same ZIP codes are ranked several ways below.
Oldest ZIP codes in Pottawattamie County
| Rank | ZIP | Mailing city | Median age | Residents | Households | Residential mailboxes |
|---|---|---|---|---|---|---|
| 1 | 51577 | Walnut | 64.9 ±3.2 | 1,561 | 406 | — |
| 2 | 51535 | Griswold | 50.4 ±5.1 | 1,697 | 740 | — |
| 3 | 51575 | Treynor | 48.1 ±7.2 | 1,609 | 622 | — |
| 4 | 51525 | Carson | 46.7 ±7.6 | 1,067 | 464 | — |
| 5 | 51521 | Avoca | 45.2 ±4.8 | 1,953 | 878 | — |
| 6 | 51526 | Crescent | 44.3 ±13.6 | 1,664 | 643 | 642 |
| 7 | 51555 | Missouri Valley | 42.6 ±2.8 | 4,952 | 2,148 | — |
| 8 | 51560 | Oakland | 41.9 ±4.3 | 1,772 | 713 | 805 |
| 9 | 51503 | Council Bluffs | 40.6 ±1.2 | 37,972 | 15,442 | — |
| 10 | 51576 | Underwood | 40.1 ±5.5 | 1,769 | 650 | 689 |
| 11 | 51510 | Carter Lake | 40.0 ±5.6 | 3,767 | 1,390 | 1,476 |
| 12 | 51570 | Shelby | 38.6 ±5.5 | 1,118 | 499 | 363 |
| 13 | 51501 | Council Bluffs | 38.0 ±1.3 | 34,618 | 14,271 | — |
| 14 | 51559 | Neola | 37.4 ±5.0 | 1,841 | 699 | — |
How we ranked them
Ranked by median age of all residents, highest first (ACS 5-year estimates, 2020–2024). ZIP codes need at least 1,000 residents to be ranked; 14 of 23 qualify.
Which of these to mail, and why
Older ZIP codes respond to health care, hearing and vision, Medicare plans, home safety, estate planning and services that come to the door.
The top five ZIP codes on this list hold 3,110 households. Open any of them on the route map to see each carrier route's own figures before you choose.
Open 51577 on the EDDM route map
More rankings
- Richest ZIP codes in Pottawattamie County
- ZIP codes with the highest home values in Pottawattamie County
- ZIP codes with the highest homeownership in Pottawattamie County
- ZIP codes with the most families with kids in Pottawattamie County
- ZIP codes with the most new movers in Pottawattamie County
- Youngest ZIP codes in Pottawattamie County
- Fastest-growing ZIP codes in Pottawattamie County
- All Pottawattamie County ZIP codes
Businesses that mail these ZIP codes
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EDDM guides
Frequently asked questions
- Which ZIP code in Pottawattamie County has the highest median age?
- 51577 (Walnut), at 64.9 (±3.2), among 14 ZIP codes with at least 1,000 residents.
- How is this ranking calculated?
- Ranked by median age of all residents, highest first (ACS 5-year estimates, 2020–2024).
- Why are some ZIP codes missing?
- ZIP codes with fewer than 1,000 residents are left out because their survey estimates swing too much to rank, and so are ZIP codes where the Census Bureau did not publish this figure.
This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.