County profile · official public datasets

Allegan County, MI

244 public highway bridges tracked in the FHWA National Bridge Inventory: 24.2% rated Good, 59% Fair, 16.8% Poor.

244
Public bridges: 24.2%
Good condition: 16.8%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Allegan County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

65th
of 83 on Poor share: 16.8%
Poor-condition share: 244
public highway bridges: 1978
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Allegan County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Allegan County ranks #65 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 16.8%). Allegan County, Michigan contains 244 public highway bridges. Roughly 24.2% are rated “Good,” 59% “Fair,” and 16.8% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

244

Public highway bridges in Allegan County

Good condition

24.2%

59 of 244 rated 7-9

Fair condition

59%

144 of 244 rated 5-6

Poor condition

16.8%

41 of 244 rated 4 or below

In-state Poor-share rank

#65 of 83

Among Michigan counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 244 NBI-tracked bridges by lowest applicable component rating.

Good

24.2% (59)

Fair

59% (144)

Poor

16.8% (41)

Allegan County's Poor-condition bridges carry 81,607 vehicle crossings a day

That is 8.8% of the county's reported daily bridge traffic on 16.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,990 crossings a day against 2,254 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 244 of 244 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

51.2% of Allegan County's bridges have passed the 50-year mark

125 of the 244 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 24.2% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 34.2% of the county's Poor-condition bridge traffic

US-131 SB over GRAND ELK RR, built 1960, carries 27,941 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 41-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 81,607 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1920s

4
1930s

6
1940s

4
1950s

14
1960s

44
1970s

76
1980s

34
1990s

17
2000s

20
2010s

20
2020s

4

What this shows Construction peaked in the 1970s, when 76 of the county's bridges still in the inventory were built, which is 31.1% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1978) matches the Michigan average (1976).

How Allegan County compares with Michigan's closest counties by inventory size

The 5 Michigan counties nearest Allegan County in number of bridges, with their condition splits. Its 16.8% Poor share is the 5th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1977 is in line with the group.

Showing the 5 closest of 82 Michigan counties eligible for comparison.

Bridge inventory size and condition shares for Allegan County and the 5 Michigan counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Washtenaw County	262	23.3%	56.5%	20.2%	1975
Ottawa County	254	40.9%	52.8%	6.3%	1977
Allegan County (this page)	244	24.2%	59%	16.8%	1978
Tuscola County	242	33.9%	61.2%	5%	1980
Ingham County	241	15.8%	68.9%	15.4%	1972
Lenawee County	225	47.6%	39.6%	12.9%	1981

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Allegan County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Allegan County, both outside Michigan so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MI (244 bridges here).

Spencer County, IN · 244 bridges
Norton County, KS · 244 bridges
Osborne County, KS · 244 bridges
Seward County, NE · 244 bridges

Similar average build year

Nearest mean year-built outside MI (1978 here).

Orange County, CA · avg 1978 · 1,164 bridges
Sumner County, KS · avg 1978 · 659 bridges
Allen County, IN · avg 1978 · 613 bridges
Livingston County, IL · avg 1978 · 579 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 244 Good 59 Fair 144 Poor 41

All bridges (244)

Sort:

30TH STREET

Good

Over: LITTLE RABBIT RIVER

APPROX 0.10 MI S OF 142ND, Allegan, MI

Built 1947 Load: 83.6 t ADT: 5,818

137TH AVENUE

Good

Over: PIGEON CREEK

SALEM TWP SEC 34, Allegan, MI

Built 1979 Load: 86.5 t ADT: 185

I-196

Good

Over: PLUMMERVILLE CREEK

0.2 MI N OF 120TH AVENUE, Allegan, MI

Allegan County Bridge Snapshot

Condition distribution

Allegan County's Poor-condition bridges carry 81,607 vehicle crossings a day

51.2% of Allegan County's bridges have passed the 50-year mark

One structure carries 34.2% of the county's Poor-condition bridge traffic

How Allegan County compares with Michigan's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (244)

30TH STREET

137TH AVENUE

I-196

16TH STREET

47TH STREET

144TH AVE

116TH AVE

16TH STREET

144TH AVE

14TH STREET

7TH STREET

RUSSCHER ROAD

130TH AVE

107TH AVE

21ST STREET

20TH STREET

103RD AVE

63RD STREET

62ND STREET

114TH AVE

140TH AVE

WILLIAMS ROAD

118TH AVE

68TH STREET

133RD AVENUE

70TH STREET

DIVISION STREET

46TH STREET

RIVERSIDE ROAD

144TH AVE

146TH AVE

64TH STREET

M-40 M-89

147TH AVE

US-131 SB

OTTOGAN STREET

I-196 EB

147TH AVE

142ND AVE

60TH STREET

140TH AVE

107TH AVE

16TH STREET

18TH ST

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