County profile · official public datasets

Missoula County, MT

206 public highway bridges tracked in the FHWA National Bridge Inventory: 33.5% rated Good, 58.7% Fair, 7.8% Poor.

206
Public bridges
33.5%
Good condition
7.8%
Poor condition

The verdict

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

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

39th
of 56 on Poor share
7.8%
Poor-condition share
206
public highway bridges
1976
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.

Missoula County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Missoula County ranks #39 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.8%). Missoula County, Montana contains 206 public highway bridges. Roughly 33.5% are rated “Good,” 58.7% “Fair,” and 7.8% “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

206

Public highway bridges in Missoula County

Good condition

33.5%

69 of 206 rated 7-9

Fair condition

58.7%

121 of 206 rated 5-6

Poor condition

7.8%

16 of 206 rated 4 or below

In-state Poor-share rank

#39 of 56

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

Condition distribution

Share of 206 NBI-tracked bridges by lowest applicable component rating.

Good
33.5% (69)
Fair
58.7% (121)
Poor
7.8% (16)

Missoula County's Poor-condition bridges carry 32,823 vehicle crossings a day

That is 3.7% of the county's reported daily bridge traffic on 7.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,051 crossings a day against 3,889 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 206 of 206 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

55.8% of Missoula County's bridges have passed the 50-year mark

115 of the 206 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 33.5% 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 40.4% of the county's Poor-condition bridge traffic

I 90 over INT RESERVE STREET, built 1966, carries 13,266 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 16-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 32,823 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Missoula County's bridges were built

206 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 63 of the county's bridges still in the inventory were built, which is 30.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1976) matches the Montana average (1977).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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

The 5 Montana counties nearest Missoula County in number of bridges, with their condition splits. Its 7.8% Poor share is the 4th-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Missoula County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Beaverhead County 226 9.3%
Gallatin County 210 4.3%
Missoula County (this page) 206 7.8%
Flathead County 204 4.9%
Lewis and Clark County 200 5.5%
Lincoln County 190 14.7%

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

Similar inventory size

Nearest county inventories outside MT (206 bridges here).

Similar average build year

Nearest mean year-built outside MT (1976 here).

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

All 206 Good 69 Fair 121 Poor 16

Fair-condition bridges (121)

KONA RANCH RD

Fair

Over: CLARK FORK 011

8M W MISSOULA, Missoula, MT

Built 1987 Load: 36.3 t ADT: 100

I 90

Fair

Over: INT BEAVERTAIL

7.4M W BEARMOUTH, Missoula, MT

Built 1972 Load: 37.2 t ADT: 6,316

US 93

Fair

Over: INT DESMET I 90

5M NW MISSOULA, Missoula, MT

Built 1995 Load: 37.2 t ADT: 7,676

GILLESPIE SLIDEROC

Fair

Over: CLARK FORK

GILLESPIE-SLIDEROCK, Missoula, MT

Built 1965 Load: 37.6 t ADT: 50

I 90

Fair

Over: INT LOTHROP

2.5M E ALBERTON, Missoula, MT

Built 1963 Load: 38.1 t ADT: 4,525

I 90 WB

Fair

Over: INT VAN BUREN STREET

MISSOULA, Missoula, MT

Built 1964 Load: 38.1 t ADT: 14,839

STYLER DR

Fair

Over: GLACIER CR OVRFLOW 060

2M SW CONDON, Missoula, MT

Built 1974 Load: 38.1 t ADT: 100

S 200

Fair

Over: BLACKFOOT RIVER

4M E BONNER, Missoula, MT

Built 1968 Load: 38.1 t ADT: 4,601

S 200

Fair

Over: CLEARWATER RIVER

CLEARWATER JCT, Missoula, MT

Built 1949 Load: 38.1 t ADT: 3,070

KRAFT CREEK RD

Fair

Over: GLACIER CREEK

KRAFT CK RD AT GLACIER CK, Missoula, MT

Built 2019 Load: 38.2 t ADT: 10

COLD CREEK RD

Fair

Over: SWAN RIVER 045

1M N CONDON, Missoula, MT

Built 1954 Load: 39.9 t ADT: 100

I 90

Fair

Over: INT NINE MILE

6.8M W FRENCHTOWN, Missoula, MT

Built 1964 Load: 41.7 t ADT: 5,428

I 90

Fair

Over: CLARK FORK RIVER

5M E ALBERTON, Missoula, MT

Built 1979 Load: 43.5 t ADT: 4,525

S 200

Fair

Over: BLACKFOOT RIVER

1M W BONNER, Missoula, MT

Built 2009 Load: 43.5 t ADT: 8,131

IRR - US 93

Fair

Over: RR-FINLEY CREEK

14M N MISSOULA, Missoula, MT

Built 2009 Load: 44.5 t ADT: 8,184

EAST FK LOLO CR

Fair

Over: LOLO CREEK

EAST FK LOLO, Missoula, MT

Built 1946 Load: 47.0 t ADT: 50

I 90

Fair

Over: DEER CREEK ROAD

1.9M W BONNER, Missoula, MT

Built 1964 Load: 49.9 t ADT: 9,994

FOREST ROAD

Fair

Over: GLACIER CREEK

ELK CREEK ROAD, Missoula, MT

Built 1981 Load: 55.4 t ADT: 10

IRR BIA RTE 1015

Fair

Over: HICKS CREEK

26 KM EAST OF ARLEE, Missoula, MT

Built 2001 Load: 59.9 t ADT: 20

US 93

Fair

Over: WILDLIFE UNDERPASS

10M N WYE JCT, Missoula, MT

Built 2009 Load: 64.4 t ADT: 8,184

S HOLLAND LAKE RD

Fair

Over: HOLLAND CREEK 051

HOLLAND LAKE, Missoula, MT

Built 1949 Load: 72.6 t ADT: 100

Read our methodology - how this data is sourced, computed, and verified.

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.