Which ZIP code in Boulder County has the highest median age?

80540 (Lyons), at 48.1 (±2.8), among 15 ZIP codes with at least 1,000 residents.

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.

Oldest ZIP codes in Boulder County, CO

These are the 15 ZIP codes in Boulder County with the highest median age, out of 15 with at least 1,000 residents. 80540 (Lyons, 48.1), 80503 (Longmont, 44.8) and 80466 (Nederland, 43.6) lead the list. There is no single "best" ZIP code in Boulder 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 Boulder County

Rank	ZIP	Mailing city	Median age	Residents	Households	Residential mailboxes
1	80540	Lyons	48.1 ±2.8	4,642	2,025	1,402
2	80503	Longmont	44.8 ±1.4	35,846	15,153	15,573
3	80466	Nederland	43.6 ±5.4	3,599	1,670	710
4	80304	Boulder	42.8 ±2.2	25,383	11,358	12,139
5	80027	Louisville	40.3 ±2.2	34,127	13,180	14,806
6	80026	Lafayette	40.0 ±1.8	32,701	13,524	15,023
7	80504	Longmont	39.5 ±0.9	63,451	24,077	25,785
8	80501	Longmont	38.4 ±1.8	44,147	18,945	19,651
9	80020	Broomfield	37.7 ±0.6	54,201	21,326	22,532
10	80516	Erie	37.7 ±0.8	39,048	13,616	14,966
11	80301	Boulder	36.9 ±1.7	25,007	12,371	13,814
12	80305	Boulder	36.7 ±2.1	16,291	6,976	7,285
13	80303	Boulder	29.3 ±1.2	24,996	11,783	12,581
14	80302	Boulder	24.9 ±1.5	29,569	12,425	12,329
15	80310	Boulder	19.3 ±0.2	7,692	2	—

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; 15 of 21 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 43,386 households, on 81 carrier routes with 44,630 residential mailboxes. Open any of them on the route map to see each carrier route's own figures before you choose.

Open 80540 on the EDDM route map

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Businesses that mail these ZIP codes

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Frequently asked questions

Which ZIP code in Boulder County has the highest median age?: 80540 (Lyons), at 48.1 (±2.8), among 15 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.