County profile · official public datasets

Mahnomen County, MN

40 public highway bridges tracked in the FHWA National Bridge Inventory: 67.5% rated Good, 27.5% Fair, 5% Poor.

40
Public bridges: 67.5%
Good condition: 5%
Poor condition

The verdict

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

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

56th
of 87 on Poor share: 5%
Poor-condition share: 40
public highway bridges: 1987
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.

Mahnomen County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Mahnomen County ranks #56 of 87 Minnesota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5%). Mahnomen County, Minnesota contains 40 public highway bridges. Roughly 67.5% are rated “Good,” 27.5% “Fair,” and 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

Public highway bridges in Mahnomen County

Good condition

67.5%

27 of 40 rated 7-9

Fair condition

27.5%

11 of 40 rated 5-6

Poor condition

2 of 40 rated 4 or below

In-state Poor-share rank

#56 of 87

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

Condition distribution

Share of 40 NBI-tracked bridges by lowest applicable component rating.

Good

67.5% (27)

Fair

27.5% (11)

Poor

5% (2)

Mahnomen County's Poor-condition bridges carry 154 vehicle crossings a day

That is 1.2% of the county's reported daily bridge traffic on 5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 77 crossings a day against 270 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 40 of 40 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

15% of Mahnomen County's bridges have passed the 50-year mark

6 of the 40 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 67.5% 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 97.4% of the county's Poor-condition bridge traffic

CSAH 5 over WILD RICE RIVER, built 1966, carries 150 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 154 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

1
1960s

3
1970s

10
1980s

14
1990s

2
2000s

5
2010s

2
2020s

3

What this shows Construction peaked in the 1980s, when 14 of the county's bridges still in the inventory were built, which is 35% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1987) matches the Minnesota average (1986).

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

The 5 Minnesota counties nearest Mahnomen County in number of bridges, with their condition splits. Its 5% Poor share is the 4th-lowest of these 6. Its average build year of 1987 against a peer-group mean of 1987 is in line with the group.

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

Bridge inventory size and condition shares for Mahnomen County and the 5 Minnesota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Pope County	47	87.2%	10.6%	2.1%	1987
Hubbard County	45	55.6%	42.2%	2.2%	1990
Stevens County	44	65.9%	29.5%	4.5%	1982
Douglas County	40	45%	47.5%	7.5%	1981
Mahnomen County (this page)	40	67.5%	27.5%	5%	1987
Isanti County	37	51.4%	43.2%	5.4%	1997

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

Similar inventory size

Nearest county inventories outside MN (40 bridges here).

Taliaferro County, GA · 40 bridges
Clark County, ID · 40 bridges
St. John the Baptist County, LA · 40 bridges
Dare County, NC · 40 bridges

Similar average build year

Nearest mean year-built outside MN (1987 here).

St. Louis County, MO · avg 1987 · 912 bridges
Ellis County, TX · avg 1987 · 691 bridges
Palm Beach County, FL · avg 1987 · 610 bridges
Dane County, WI · avg 1987 · 590 bridges

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

All 40 Good 27 Fair 11 Poor 2

All bridges (40)

Sort:

CSAH 11

Fair

Over: WHITE EARTH RIVER

0.7 MI E OF JCT TH 59, Mahnomen, MN

Built 1966 Load: 20.0 t ADT: 335

CSAH 4

Fair

Over: WILD RICE RIVER

0.6 MI S OF JCT CSAH 14, Mahnomen, MN

Built 1981 Load: 25.8 t ADT: 310

CR 130

Fair

Over: MARSH CREEK

2.1 MI W OF JCT TH 59, Mahnomen, MN

Built 1976 Load: 27.1 t ADT: 30

CR 113

Fair

Over: WHITE EARTH RIVER

1.4 MI NE OF JCT TH 113, Mahnomen, MN

Built 1977 Load: 29.4 t ADT: 70

T 39

Fair

Over: MARSH CREEK (CD #91-91A)

0.9 MI W OF JCT TH 59, Mahnomen, MN

Built 1985 Load: 29.4 t ADT: 25

CSAH 7

Fair

Over: SAND HILL RIVER

2.2 MI N OF JCT CSAH 1, Mahnomen, MN

Built 1966 Load: 30.8 t ADT: 50

T 15

Fair

Over: MARSH CREEK (JD # 91)

1.2 MI N OF JCT CSAH 1, Mahnomen, MN

Built 1978 Load: 32.4 t ADT: 7

T 314

Fair

Over: WILD RICE RIVER

2.4 MI S OF JCT CSAH 14, Mahnomen, MN

Built 1984 Load: 32.6 t ADT: 30

CSAH 2

Fair

Over: WILD RICE RIVER

0.8 MI N OF JCT TH200, Mahnomen, MN

Built 1980 Load: 35.6 t ADT: 140

CR 135

Fair

Over: WILD RICE RIVER

0.6 MI N OF JCT TH 200, Mahnomen, MN

Built 1986 Load: 38.9 t ADT: 50

US 59

Fair

Over: WILD RICE RIVER

1.4 MI S OF JCT TH 200, Mahnomen, MN

Mahnomen County Bridge Snapshot

Condition distribution

Mahnomen County's Poor-condition bridges carry 154 vehicle crossings a day

15% of Mahnomen County's bridges have passed the 50-year mark

One structure carries 97.4% of the county's Poor-condition bridge traffic

How Mahnomen 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

All bridges (40)

CSAH 11

CSAH 4

CR 130

CR 113

T 39

CSAH 7

T 15

T 314

CSAH 2

CR 135

US 59

CSAH 3

T 132

MN 200

MN 113

CSAH 9

CR 121

T 100

T 41

T 83

T 243

T 128

CSAH 25

T 75

CSAH 12

T 108

T 128

T 102

T 23

CR 101

CSAH 25

CR 107

CSAH 6

CSAH 10

T 22

MN 200

MN 200

CR 132

T 76

CSAH 5

Related