County profile · official public datasets

Kent County, MI

523 public highway bridges tracked in the FHWA National Bridge Inventory: 36.9% rated Good, 57.7% Fair, 5.4% Poor.

523
Public bridges: 36.9%
Good condition: 5.4%
Poor condition

The verdict

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

Kent County posts a top-quartile lowest Poor-condition share among rated counties in the state across large county bridge inventory.

Top 16%
lowest Poor share in state: 5.4%
Poor-condition share: 523
public highway bridges: 1975
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.

Kent County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Kent County ranks #13 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.4%). Kent County, Michigan contains 523 public highway bridges. Roughly 36.9% are rated “Good,” 57.7% “Fair,” and 5.4% “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

523

Public highway bridges in Kent County

Good condition

36.9%

193 of 523 rated 7-9

Fair condition

57.7%

302 of 523 rated 5-6

Poor condition

5.4%

28 of 523 rated 4 or below

In-state Poor-share rank

#13 of 83

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

Condition distribution

Share of 523 NBI-tracked bridges by lowest applicable component rating.

Good

36.9% (193)

Fair

57.7% (302)

Poor

5.4% (28)

Kent County's Poor-condition bridges carry 574,530 vehicle crossings a day

That is 6.8% of the county's reported daily bridge traffic on 5.4% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 20,519 crossings a day against 12,442 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 519 of 523 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

55.4% of Kent County's bridges have passed the 50-year mark

290 of the 523 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 36.9% 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 8.9% of the county's Poor-condition bridge traffic

I-296 (US-131) NB over US-131 BR (LEONARD), built 1961, carries 50,972 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 28-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 574,530 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

2
1910s

2
1920s

22
1930s

13
1940s

10
1950s

13
1960s

188
1970s

71
1980s

39
1990s

38
2000s

104
2010s

14
2020s

7

What this shows Construction peaked in the 1960s, when 188 of the county's bridges still in the inventory were built, which is 35.9% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1975) matches the Michigan average (1976).

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

The 5 Michigan counties nearest Kent County in number of bridges, with their condition splits. Its 5.4% Poor share is the 1st-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Kent County and the 5 Michigan counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Kent County (this page)	523	36.9%	57.7%	5.4%	1975
Oakland County	508	41.5%	51%	7.5%	1982
Macomb County	417	42.7%	49.6%	7.7%	1980
Genesee County	371	22.9%	61.7%	15.4%	1968
St. Clair County	327	41.3%	50.5%	8.3%	1985
Saginaw County	315	28.9%	52.7%	18.4%	1979

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 Kent 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 Kent County, both outside Michigan so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MI (523 bridges here).

Madison County, IL · 523 bridges
Rapides County, LA · 523 bridges
Williamson County, TN · 520 bridges
New Castle County, DE · 527 bridges

Similar average build year

Nearest mean year-built outside MI (1975 here).

San Bernardino County, CA · avg 1975 · 1,422 bridges
Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges

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

All 523 Good 193 Fair 302 Poor 28

All bridges (523)

Sort:

Kent County Bridge Snapshot

Condition distribution

Kent County's Poor-condition bridges carry 574,530 vehicle crossings a day

55.4% of Kent County's bridges have passed the 50-year mark

One structure carries 8.9% of the county's Poor-condition bridge traffic

How Kent 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 (523)

I-196 EB

20 MILE RD

BURTON STREET

MADISON AVENUE

EB I-196 ON RAMP

VETERANS MEMORIAL

M-6 EB

M-6 WB

M-6 WB

M-6 WB

I-96 EB

CANNONSBURG RD

ROGUE RIVER RD

M-6 EB

M-6 EB

M-6 EB TO US-131SB

68TH STREET

I-196 EB M-21

US-131 SB

M-6 EB TO I-96 WB

CASCADE RD WB

6 MILE ROAD

I-196 M-21 WB

M-6 WB C-D

M-6(RMP B TO I-96)

I-96 EB RAMP B

I-96 WB

I-196 M-21 WB

BUTTRICK AVE

M-6 WB

THORNAPPLE RVR DR

M-6 EB C-D

I-196 WB M-21

INDIAN LAKE RD

COURTLAND DRIVE

18 MILE ROAD

36TH STREET

M-6 WB

I-96 WB

INDIAN LAKE RD

VINTON AVE

M-6

I-196 M-21 EB

M-6 WB

M-6 EB

100TH STREET

M-6 EB C-D

SOUTH MAIN ST

ALGOMA AVE

COLDWATER AVE

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