County profile · official public datasets

St. Croix County, WI

298 public highway bridges tracked in the FHWA National Bridge Inventory: 68.1% rated Good, 28.9% Fair, 3% Poor.

298
Public bridges: 68.1%
Good condition: 3%
Poor condition

The verdict

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

St. Croix County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 11%
lowest Poor share in state: 3%
Poor-condition share: 298
public highway bridges: 1986
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.

St. Croix County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, St. Croix County ranks #8 of 72 Wisconsin counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3%). St. Croix County, Wisconsin contains 298 public highway bridges. Roughly 68.1% are rated “Good,” 28.9% “Fair,” and 3% “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

298

Public highway bridges in St. Croix County

Good condition

68.1%

203 of 298 rated 7-9

Fair condition

28.9%

86 of 298 rated 5-6

Poor condition

9 of 298 rated 4 or below

In-state Poor-share rank

#8 of 72

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

Condition distribution

Share of 298 NBI-tracked bridges by lowest applicable component rating.

Good

68.1% (203)

Fair

28.9% (86)

Poor

3% (9)

St. Croix County's Poor-condition bridges carry 40,970 vehicle crossings a day

That is 3% of the county's reported daily bridge traffic on 3% of its bridges: Poor-condition structures carry the same share of traffic than their share of the inventory. Each Poor bridge averages 4,552 crossings a day against 4,345 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 298 of 298 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

29.2% of St. Croix County's bridges have passed the 50-year mark

87 of the 298 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 68.1% 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 43.4% of the county's Poor-condition bridge traffic

IH 94 EB over EAU GALLE RIVER, built 1958, carries 17,800 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 40,970 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

8
1930s

9
1940s

3
1950s

16
1960s

35
1970s

34
1980s

40
1990s

61
2000s

41
2010s

35
2020s

15

What this shows Construction peaked in the 1990s, when 61 of the county's bridges still in the inventory were built, which is 20.5% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year (1986) matches the Wisconsin average (1984).

How St. Croix County compares with Wisconsin's closest counties by inventory size

The 5 Wisconsin counties nearest St. Croix County in number of bridges, with their condition splits. Its 3% Poor share is the 1st-lowest of these 6. Its average build year of 1986 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 St. Croix County and the 5 Wisconsin counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Barron County	319	48.6%	45.8%	5.6%	1978
Rock County	304	61.2%	35.2%	3.6%	1994
Richland County	298	54%	41.9%	4%	1986
St. Croix County (this page)	298	68.1%	28.9%	3%	1986
Clark County	296	54.4%	33.4%	12.2%	1983
Outagamie County	290	49.7%	46.2%	4.1%	1982

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

Similar inventory size

Nearest county inventories outside WI (298 bridges here).

Sarasota County, FL · 298 bridges
Rutherford County, NC · 298 bridges
Seminole County, OK · 298 bridges
Ada County, ID · 299 bridges

Similar average build year

Nearest mean year-built outside WI (1986 here).

El Paso County, TX · avg 1986 · 783 bridges
Caddo County, LA · avg 1986 · 682 bridges
Weld County, CO · avg 1986 · 614 bridges
Polk County, IA · avg 1986 · 545 bridges

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

All 298 Good 203 Fair 86 Poor 9

Fair-condition bridges (86)

Sort:

St. Croix County Bridge Snapshot

Condition distribution

St. Croix County's Poor-condition bridges carry 40,970 vehicle crossings a day

29.2% of St. Croix County's bridges have passed the 50-year mark

One structure carries 43.4% of the county's Poor-condition bridge traffic

How St. Croix 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 (86)

CTH J

CTH C

CTH Y

CTH Q

LRD POLK ST- CROIX

LRD 140TH AVE

LRD 100TH ST

CTH BB

LRD 170TH AVE

CTH D

LRD 250TH ST

LRD 80TH AVE

CTH E

CTH JJ

STH 128-OAK ST

LRD 200TH ST

LRD 120TH ST

CTH X

CTH E

LRD 220TH AVE

LRD 160TH ST

CTH E

LRD 220TH ST

LRD 290TH ST

LRD 240TH ST

CTH JJ

CTH E

LRD 100TH AVE

LRD 250TH ST.

STH 128

IH 94 WB

IH 94 EB

STH 65

CTH VV

IH 94 WB-USH 12 WB

CTH B RIVER ST

USH 12

CTH N

STH 35-2ND ST

LRD MAIN STREET

LRD 220TH ST

LRD RUSTIC RD #4

LRD 10TH AVE

CTH K

STH 65

LRD RUSTIC RD #3

LRD 11TH ST

STH 29

USH 12

IH 94 EB-USH 12 EB

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