County profile · official public datasets

St. Louis County, MN

663 public highway bridges tracked in the FHWA National Bridge Inventory: 50.4% rated Good, 42.8% Fair, 6.8% Poor.

663
Public bridges: 50.4%
Good condition: 6.8%
Poor condition

The verdict

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

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

67th
of 87 on Poor share: 6.8%
Poor-condition share: 663
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.

St. Louis County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, St. Louis County ranks #67 of 87 Minnesota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.8%). St. Louis County, Minnesota contains 663 public highway bridges. Roughly 50.4% are rated “Good,” 42.8% “Fair,” and 6.8% “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

663

Public highway bridges in St. Louis County

Good condition

50.4%

334 of 663 rated 7-9

Fair condition

42.8%

284 of 663 rated 5-6

Poor condition

6.8%

45 of 663 rated 4 or below

In-state Poor-share rank

#67 of 87

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

Condition distribution

Share of 663 NBI-tracked bridges by lowest applicable component rating.

Good

50.4% (334)

Fair

42.8% (284)

Poor

6.8% (45)

St. Louis County's Poor-condition bridges carry 117,824 vehicle crossings a day

That is 6.6% of the county's reported daily bridge traffic on 6.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,618 crossings a day against 2,242 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 663 of 663 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

27.1% of St. Louis County's bridges have passed the 50-year mark

180 of the 663 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 50.4% 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 28% of the county's Poor-condition bridge traffic

I 535 over ST LOUIS R; RR STREET, built 1961, carries 33,021 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 45-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 117,824 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

9
1920s

8
1930s

26
1940s

24
1950s

28
1960s

59
1970s

61
1980s

139
1990s

67
2000s

63
2010s

137
2020s

41

What this shows Construction peaked in the 1980s, when 139 of the county's bridges still in the inventory were built, which is 21% 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 St. Louis County compares with Minnesota's closest counties by inventory size

The 5 Minnesota counties nearest St. Louis County in number of bridges, with their condition splits. Its 6.8% Poor share is the 5th-lowest of these 6. Its average build year of 1987 against a peer-group mean of 1985 is in line with the group.

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

Bridge inventory size and condition shares for St. Louis County and the 5 Minnesota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Hennepin County	936	40.6%	55.3%	4.1%	1984
St. Louis County (this page)	663	50.4%	42.8%	6.8%	1987
Olmsted County	365	64.1%	34.5%	1.4%	1985
Fillmore County	348	33.3%	63.8%	2.9%	1984
Mower County	343	44.6%	47.2%	8.2%	1988
Ramsey County	341	35.5%	58.1%	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 St. Louis 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. Louis County, both outside Minnesota so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MN (663 bridges here).

Hinds County, MS · 663 bridges
Jefferson County, KY · 662 bridges
Lancaster County, NE · 661 bridges
Bell County, TX · 660 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 663 Good 334 Fair 284 Poor 45

All bridges (663)

Sort:

St. Louis County Bridge Snapshot

Condition distribution

St. Louis County's Poor-condition bridges carry 117,824 vehicle crossings a day

27.1% of St. Louis County's bridges have passed the 50-year mark

One structure carries 28% of the county's Poor-condition bridge traffic

How St. Louis 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 (663)

M 330

M 846

T 1419

CR 848

CSAH 10

CR 207

UT 9223

CR 526

MSAS 140

MSAS 140

M 277

MN 23

CSAH 110

UNDETERMINED RD

CR 688

CSAH 80

CR 245

CR 547

CSAH 4

T 5

CR 344

T 1403

CSAH 4

CSAH 133

CSAH 40

CR 766

CON 718

I 35

CON 6302

CSAH 4

UT 9218

CR 836

I 35

CSAH 24

CSAH 50

CSAH 11

CR 340

SERVICE RD

CSAH 40

CON 719

CSAH 61

CSAH 4

CON 3537

UT 9253

CSAH 92

M 846

CSAH 23

VERMILION FALLS RD

CSAH 48

CSAH 8

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