County profile · official public datasets

Carlton County, MN

147 public highway bridges tracked in the FHWA National Bridge Inventory: 51.7% rated Good, 39.5% Fair, 8.8% Poor.

147
Public bridges: 51.7%
Good condition: 8.8%
Poor condition

The verdict

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

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

81st
of 87 on Poor share: 8.8%
Poor-condition share: 147
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.

Carlton County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Carlton County ranks #81 of 87 Minnesota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.8%). Carlton County, Minnesota contains 147 public highway bridges. Roughly 51.7% are rated “Good,” 39.5% “Fair,” and 8.8% “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

147

Public highway bridges in Carlton County

Good condition

51.7%

76 of 147 rated 7-9

Fair condition

39.5%

58 of 147 rated 5-6

Poor condition

8.8%

13 of 147 rated 4 or below

In-state Poor-share rank

#81 of 87

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

Condition distribution

Share of 147 NBI-tracked bridges by lowest applicable component rating.

Good

51.7% (76)

Fair

39.5% (58)

Poor

8.8% (13)

Carlton County's Poor-condition bridges carry 29,073 vehicle crossings a day

That is 6.2% of the county's reported daily bridge traffic on 8.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,236 crossings a day against 1,935 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 147 of 147 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

38.8% of Carlton County's bridges have passed the 50-year mark

57 of the 147 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 51.7% 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 30.4% of the county's Poor-condition bridge traffic

I 35 over CSAH 61, built 1965, carries 8,850 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 29,073 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

1
1930s

3
1940s

1
1950s

4
1960s

33
1970s

22
1980s

17
1990s

14
2000s

12
2010s

28
2020s

11

What this shows Construction peaked in the 1960s, when 33 of the county's bridges still in the inventory were built, which is 22.4% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1986) matches the Minnesota average (1986).

How Carlton County compares with Minnesota's closest counties by inventory size

The 5 Minnesota counties nearest Carlton County in number of bridges, with their condition splits. Its 8.8% Poor share is the 6th-lowest of these 6. Its average build year of 1986 against a peer-group mean of 1984 is in line with the group.

Showing the 5 closest of 86 Minnesota counties eligible for comparison.

Bridge inventory size and condition shares for Carlton County and the 5 Minnesota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Anoka County	151	55%	40.4%	4.6%	1990
Cottonwood County	151	74.8%	23.8%	1.3%	1981
Norman County	149	75.2%	21.5%	3.4%	1983
Otter Tail County	149	40.9%	52.3%	6.7%	1980
Wabasha County	147	60.5%	39.5%	0%	1985
Carlton County (this page)	147	51.7%	39.5%	8.8%	1986

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

Similar inventory size

Nearest county inventories outside MN (147 bridges here).

Barren County, KY · 147 bridges
Avoyelles County, LA · 147 bridges
Marquette County, MI · 147 bridges
Craven County, NC · 147 bridges

Similar average build year

Nearest mean year-built outside MN (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 147 Good 76 Fair 58 Poor 13

Good-condition bridges (76)

Sort:

Carlton County Bridge Snapshot

Condition distribution

Carlton County's Poor-condition bridges carry 29,073 vehicle crossings a day

38.8% of Carlton County's bridges have passed the 50-year mark

One structure carries 30.4% of the county's Poor-condition bridge traffic

How Carlton County compares with Minnesota'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 (76)

I 35

I 35

T 213

T 42

MN 210

T 178

CSAH 13

I 35

I 35

T 389

CR 138

I 35

I 35

I 35

CSAH 4

CR 151

CSAH 21

I 35

CSAH 23

CR 157

CR 112

CR 157

CR 124

CR 124

CSAH 12

CSAH 2

T 274

CSAH 8

CSAH 5

MN 210

MN 210

MN 210

MN 210

MN 210

CSAH 61

CR 130

CR 156

CSAH 27

T 1265

T 432

CSAH 23

T 177

T 287

MN 23

CSAH 6

MN 73

CR 103

T 542

CSAH 22

T 43

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