Which ZIP code in LaSalle County has the lowest median age?

61360 (Seneca), at 37.9 (±10.2), among 16 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.

Youngest ZIP codes in LaSalle County, IL

These are the 16 ZIP codes in LaSalle County with the lowest median age, out of 16 with at least 1,000 residents. 61360 (Seneca, 37.9), 60531 (Leland, 38.2) and 60548 (Sandwich, 40.8) lead the list. There is no single "best" ZIP code in LaSalle County; the right one depends on who you want to reach, so the same ZIP codes are ranked several ways below.

Youngest ZIP codes in LaSalle County

Rank	ZIP	Mailing city	Median age	Residents	Households	Residential mailboxes
1	61360	Seneca	37.9 ±10.2	3,610	1,363	1,032
2	60531	Leland	38.2 ±2.5	1,885	724	547
3	60548	Sandwich	40.8 ±3.2	11,721	4,548	5,002
4	61370	Tonica	41.2 ±3.2	1,215	471	416
5	61342	Mendota	41.5 ±2.8	8,543	3,487	3,545
6	61348	Oglesby	41.5 ±4.1	4,375	1,943	2,113
7	61301	La Salle	41.7 ±3.2	10,398	4,579	—
8	61364	Streator	41.9 ±1.8	17,963	8,094	8,122
9	60518	Earlville	41.9 ±4.7	3,289	1,465	1,255
10	61350	Ottawa	42.2 ±1.6	23,713	9,756	10,903
11	60551	Sheridan	42.3 ±3.7	5,058	1,546	1,179
12	61341	Marseilles	42.5 ±2.0	7,692	3,098	—
13	61373	Utica	42.7 ±5.1	2,123	802	—
14	61377	Wenona	44.3 ±9.0	1,441	699	—
15	61354	Peru	46.2 ±3.2	10,290	4,682	4,892
16	60552	Somonauk	48.6 ±6.8	4,285	1,807	1,557

How we ranked them

Ranked by median age of all residents, lowest first (ACS 5-year estimates, 2020–2024). ZIP codes need at least 1,000 residents to be ranked; 16 of 28 qualify.

Which of these to mail, and why

Younger ZIP codes skew toward renters, students and young families: fitness, quick-service food, apartments, entertainment and first-time-buyer offers.

The top five ZIP codes on this list hold 10,593 households, on 23 carrier routes with 10,542 residential mailboxes. Open any of them on the route map to see each carrier route's own figures before you choose.

Open 61360 on the EDDM route map

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Frequently asked questions

Which ZIP code in LaSalle County has the lowest median age?: 61360 (Seneca), at 37.9 (±10.2), among 16 ZIP codes with at least 1,000 residents.
How is this ranking calculated?: Ranked by median age of all residents, lowest 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.