County profile · official public datasets

Mineral County, MT

152 public highway bridges tracked in the FHWA National Bridge Inventory: 25.7% rated Good, 64.5% Fair, 9.9% Poor.

152
Public bridges: 25.7%
Good condition: 9.9%
Poor condition

The verdict

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

Mineral County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

45th
of 56 on Poor share: 9.9%
Poor-condition share: 152
public highway bridges: 1971
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.

Mineral County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Mineral County ranks #45 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.9%). Mineral County, Montana contains 152 public highway bridges. Roughly 25.7% are rated “Good,” 64.5% “Fair,” and 9.9% “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

152

Public highway bridges in Mineral County

Good condition

25.7%

39 of 152 rated 7-9

Fair condition

64.5%

98 of 152 rated 5-6

Poor condition

9.9%

15 of 152 rated 4 or below

In-state Poor-share rank

#45 of 56

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

Condition distribution

Share of 152 NBI-tracked bridges by lowest applicable component rating.

Good

25.7% (39)

Fair

64.5% (98)

Poor

9.9% (15)

Mineral County's Poor-condition bridges carry 12,876 vehicle crossings a day

That is 3.9% of the county's reported daily bridge traffic on 9.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 858 crossings a day against 1,295 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 152 of 152 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

55.9% of Mineral County's bridges have passed the 50-year mark

85 of the 152 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 25.7% 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 31.3% of the county's Poor-condition bridge traffic

I 90 over SEP ELIZABETH LN, built 1965, carries 4,036 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 15-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 12,876 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

1
1930s

6
1940s

3
1950s

24
1960s

36
1970s

25
1980s

41
1990s

4
2000s

7
2010s

3
2020s

1

What this shows Construction peaked in the 1980s, when 41 of the county's bridges still in the inventory were built, which is 27% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1971, 6 years older than the Montana average of 1977.

How Mineral County compares with Montana's closest counties by inventory size

The 5 Montana counties nearest Mineral County in number of bridges, with their condition splits. Its 9.9% Poor share is the 5th-lowest of these 6. Its average build year of 1971 against a peer-group mean of 1978 is 7 years older.

Showing the 5 closest of 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Mineral County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Fergus County	158	31.6%	62%	6.3%	1978
Mineral County (this page)	152	25.7%	64.5%	9.9%	1971
Ravalli County	148	41.2%	53.4%	5.4%	1981
Big Horn County	135	26.7%	68.1%	5.2%	1978
Jefferson County	134	17.9%	76.9%	5.2%	1977
Park County	124	21%	68.5%	10.5%	1976

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

Similar inventory size

Nearest county inventories outside MT (152 bridges here).

Logan County, AR · 152 bridges
Kosciusko County, IN · 152 bridges
Muhlenberg County, KY · 152 bridges
Clinton County, MO · 152 bridges

Similar average build year

Nearest mean year-built outside MT (1971 here).

Wayne County, MI · avg 1971 · 1,026 bridges
Baltimore County, MD · avg 1971 · 783 bridges
Washington County, PA · avg 1971 · 655 bridges
Linn County, OR · avg 1971 · 566 bridges

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

All 152 Good 39 Fair 98 Poor 15

Fair-condition bridges (98)

Sort:

Mineral County Bridge Snapshot

Condition distribution

Mineral County's Poor-condition bridges carry 12,876 vehicle crossings a day

55.9% of Mineral County's bridges have passed the 50-year mark

One structure carries 31.3% of the county's Poor-condition bridge traffic

How Mineral County compares with Montana'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 (98)

RD 431

NO DATA ENTERED

LOZEAU CROSSOVR RD

I 90

NO DATA ENTERED

SOUTHSIDE CROSSING

RD 506

I 90

RD 250

NO DATA ENTERED

I 90 EB

I 90

I 90

OLD HWY 10 E

RD 388

I 90

NO DATA ENTERED

RD 810

DIAMOND MATCH RD

I 90

I 90

I 90

I 90

I 90

I 90 WB

FISH CREEK RD

MULLAN GULCH RD

RD 450

I 90 EB

I 90

I 90

I 90

MULLAN GULCH RD

I 90

I 90

I 90

I 90

RD 352

I 90

I 90 EB

I 90

I 90

RD 352

RD 450

RD 1181

I 90 EB

I 90

I 90 WB

I 90

I 90

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