County profile · official public datasets

Eaton County, MI

200 public highway bridges tracked in the FHWA National Bridge Inventory: 30% rated Good, 63.5% Fair, 6.5% Poor.

200
Public bridges: 30%
Good condition: 6.5%
Poor condition

The verdict

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

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

Top 27%
lowest Poor share in state: 6.5%
Poor-condition share: 200
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.

Eaton County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Eaton County ranks #22 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.5%). Eaton County, Michigan contains 200 public highway bridges. Roughly 30% are rated “Good,” 63.5% “Fair,” and 6.5% “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

200

Public highway bridges in Eaton County

Good condition

30%

60 of 200 rated 7-9

Fair condition

63.5%

127 of 200 rated 5-6

Poor condition

6.5%

13 of 200 rated 4 or below

In-state Poor-share rank

#22 of 83

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

Condition distribution

Share of 200 NBI-tracked bridges by lowest applicable component rating.

Good

30% (60)

Fair

63.5% (127)

Poor

6.5% (13)

Eaton County's Poor-condition bridges carry 65,821 vehicle crossings a day

That is 5.9% of the county's reported daily bridge traffic on 6.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 5,063 crossings a day against 1,564 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 200 of 200 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

44% of Eaton County's bridges have passed the 50-year mark

88 of the 200 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 30% 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 39.8% of the county's Poor-condition bridge traffic

M-43 (W SAGINAW) over CARRIER CREEK, built 1956, carries 26,200 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 13-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 65,821 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

2
1920s

6
1930s

3
1940s

5
1950s

10
1960s

36
1970s

37
1980s

52
1990s

20
2000s

16
2010s

11
2020s

2

What this shows Construction peaked in the 1980s, when 52 of the county's bridges still in the inventory were built, which is 26% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1978) matches the Michigan average (1976).

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

The 5 Michigan counties nearest Eaton County in number of bridges, with their condition splits. Its 6.5% Poor share is the 2nd-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 Eaton County and the 5 Michigan counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Lenawee County	225	47.6%	39.6%	12.9%	1981
Clinton County	216	14.8%	69.4%	15.7%	1975
Calhoun County	213	18.3%	63.4%	18.3%	1971
Eaton County (this page)	200	30%	63.5%	6.5%	1978
Huron County	192	31.8%	62%	6.3%	1976
Isabella County	183	48.1%	38.8%	13.1%	1983

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

Similar inventory size

Nearest county inventories outside MI (200 bridges here).

Escambia County, AL · 200 bridges
Clay County, AR · 200 bridges
Parke County, IN · 200 bridges
Fayette County, KY · 200 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 200 Good 60 Fair 127 Poor 13

Good-condition bridges (60)

Sort:

Eaton County Bridge Snapshot

Condition distribution

Eaton County's Poor-condition bridges carry 65,821 vehicle crossings a day

44% of Eaton County's bridges have passed the 50-year mark

One structure carries 39.8% of the county's Poor-condition bridge traffic

How Eaton 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

Good-condition bridges (60)

MULLIKEN ROAD

IONIA ROAD

BRADFORD HWY

HARTEL ROAD

SHANCE HWY

OTTO ROAD

NASHVILLE HWY

KINSEL HWY

MATTHEWS ROAD

M-100

BROADWAY HWY

KINSEL HWY

LAMIE HWY

LAMIE HIGHWAY

ISLAND HWY

EATON HWY

BELLEVUE HWY

SHERWOOD HWY

NYE HWY

MOYER ROAD

IONIA ROAD

IONIA ROAD

FIVE POINT HWY

GRESHAM HWY

KINSEL HWY

OTTO ROAD

SPRINGPORT ROAD

LANSING RD

M-50

WAVERLY ROAD

PINCH HIGHWAY

SPICERVILLE HWY

MESSENGER HWY

M-50

JOHNSON ROAD

M-100

BASE LINE HWY

SPICERVILLE HWY

VERMONTVILLE HWY

KALAMO HWY

M-50

COLLEGE STREET

OLD M-78

WILLOW HWY

BUCK HIGHWAY

I-69 NB

MAHAN HWY

VALLEY HWY

ST JOE HWY

BROOKFIELD ROAD

Related