County profile · official public datasets

Marathon County, WI

530 public highway bridges tracked in the FHWA National Bridge Inventory: 46.4% rated Good, 43.4% Fair, 10.2% Poor.

530
Public bridges: 46.4%
Good condition: 10.2%
Poor condition

The verdict

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

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

59th
of 72 on Poor share: 10.2%
Poor-condition share: 530
public highway bridges: 1982
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.

Marathon County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Marathon County ranks #59 of 72 Wisconsin counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10.2%). Marathon County, Wisconsin contains 530 public highway bridges. Roughly 46.4% are rated “Good,” 43.4% “Fair,” and 10.2% “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

530

Public highway bridges in Marathon County

Good condition

46.4%

246 of 530 rated 7-9

Fair condition

43.4%

230 of 530 rated 5-6

Poor condition

10.2%

54 of 530 rated 4 or below

In-state Poor-share rank

#59 of 72

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

Condition distribution

Share of 530 NBI-tracked bridges by lowest applicable component rating.

Good

46.4% (246)

Fair

43.4% (230)

Poor

10.2% (54)

Marathon County's Poor-condition bridges carry 51,060 vehicle crossings a day

That is 2.3% of the county's reported daily bridge traffic on 10.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 946 crossings a day against 5,067 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 530 of 530 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

38.3% of Marathon County's bridges have passed the 50-year mark

203 of the 530 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 46.4% 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 55.1% of the county's Poor-condition bridge traffic

USH STH 52 EB-USH over WISCONSIN RIVER 31, built 1915, carries 28,144 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 54-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 51,060 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

2
1910s

1
1920s

16
1930s

21
1940s

20
1950s

38
1960s

59
1970s

68
1980s

72
1990s

75
2000s

103
2010s

34
2020s

21

What this shows Construction peaked in the 2000s, when 103 of the county's bridges still in the inventory were built, which is 19.4% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1982) matches the Wisconsin average (1984).

How Marathon County compares with Wisconsin's closest counties by inventory size

The 5 Wisconsin counties nearest Marathon County in number of bridges, with their condition splits. Its 10.2% Poor share is the 6th-lowest of these 6. Its average build year of 1982 against a peer-group mean of 1985 is in line with the group.

Showing the 5 closest of 71 Wisconsin counties eligible for comparison.

Bridge inventory size and condition shares for Marathon County and the 5 Wisconsin counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Dane County	590	51.2%	42.4%	6.4%	1987
Marathon County (this page)	530	46.4%	43.4%	10.2%	1982
Brown County	466	51.3%	44.8%	3.9%	1990
Grant County	383	66.1%	29.5%	4.4%	1984
Monroe County	374	50.5%	46%	3.5%	1981
Waukesha County	369	53.1%	40.4%	6.5%	1984

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

Similar inventory size

Nearest county inventories outside WI (530 bridges here).

Merced County, CA · 528 bridges
LaSalle County, IL · 528 bridges
Nueces County, TX · 528 bridges
New Castle County, DE · 527 bridges

Similar average build year

Nearest mean year-built outside WI (1982 here).

Oklahoma County, OK · avg 1982 · 1,216 bridges
Jackson County, MO · avg 1982 · 930 bridges
Champaign County, IL · avg 1982 · 727 bridges
Broward County, FL · avg 1982 · 686 bridges

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

All 530 Good 246 Fair 230 Poor 54

Fair-condition bridges (230)

Sort:

Marathon County Bridge Snapshot

Condition distribution

Marathon County's Poor-condition bridges carry 51,060 vehicle crossings a day

38.3% of Marathon County's bridges have passed the 50-year mark

One structure carries 55.1% of the county's Poor-condition bridge traffic

How Marathon County compares with Wisconsin's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (230)

CTH KK

STH 29

CTH N

STH 153-MAIN ST

USH B51-GRAND AVE

STH 97-WEBER AVE

STH 29 EB

STH 29 WB

STH 29 WB

LRD 14TH AVE

STH 13

CTH N

STH 97

CTH A

STH 52

CTH C

STH 107

CTH Q

STH 29

STH 97

STH 29

STH 153

STH 29 EB SYSTEM R

STH 49

CTH DB

LRD BUNGALOO RD

LRD WOODLAND RD

LRD CHESAK RD.

LRD BUTTERNUT RD

CTH P

LRD KRISTOF RD

LRD 44TH AVE

STH 107

STH 97

STH 29 EB

LRD MOON RD

CTH C

LRD ROSS AVENUE

CTH X

STH 34

LRD KONKEL RD

LRD HUCKLEBERRY RD

LRD WOODLAND DRIVE

LRD RAINBOW DR

LRD BRIDGE ST

LRD PINERY RD

CTH W

LRD DRAPER RD

STH 29 WB SYSTEM R

CTH F

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