Total bridges
206
Public highway bridges in Missoula County
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.
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
- 1900s 1
1900–1909
1 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 4
1930–1939
4 bridges
- 1940s 7
1940–1949
7 bridges
- 1950s 14
1950–1959
14 bridges
- 1960s
1960–1969
63 bridges
- 1970s
1970–1979
41 bridges
- 1980s 21
1980–1989
21 bridges
- 1990s 13
1990–1999
13 bridges
- 2000s 23
2000–2009
23 bridges
- 2010s 13
2010–2019
13 bridges
- 2020s 4
2020–2029
4 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).
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.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Beaverhead County | 226 | 23.9% | 66.8% | 9.3% | 1978 |
| Gallatin County | 210 | 19% | 76.7% | 4.3% | 1977 |
| Missoula County (this page) | 206 | 33.5% | 58.7% | 7.8% | 1976 |
| Flathead County | 204 | 30.9% | 64.2% | 4.9% | 1983 |
| Lewis and Clark County | 200 | 58% | 36.5% | 5.5% | 1979 |
| Lincoln County | 190 | 38.4% | 46.8% | 14.7% | 1977 |
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).
- Dale County, AL · 206 bridges
- Henry County, IN · 206 bridges
- Audubon County, IA · 206 bridges
- Bourbon County, KS · 206 bridges
Similar average build year
Nearest mean year-built outside MT (1976 here).
- Marion County, IN · avg 1976 · 958 bridges
- Mohave County, AZ · avg 1976 · 641 bridges
- Comanche County, OK · avg 1976 · 593 bridges
- Prince George's County, MD · avg 1976 · 576 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (16)
GILBERT CR. RD
PoorOver: ROCK CREEK
VALLEY OF THE MOON, Missoula, MT
Built 1982 ADT: 50
BOY SCOUT RD
PoorOver: CLEARWATER RIVER 082
2M NW SEELEY LAKE, Missoula, MT
Built 1938 Load: 2.7 t ADT: 100
SUNSET HILL RD
PoorOver: BLACKFOOT RIVER 088
3M S CLEARWATER JCT, Missoula, MT
Built 1907 Load: 4.5 t ADT: 100
NORTH AVE W
PoorOver: BITTERROOT RIVER 010
W MISSOULA, Missoula, MT
Built 1935 Load: 13.6 t ADT: 3,605
S 474
PoorOver: RR
4M SE FRENCHTOWN, Missoula, MT
Built 1959 Load: 22.7 t ADT: 1,371
WAHLQUIST BR ROAD
PoorOver: ROCK CREEK
AMBROSE ROCK CR, Missoula, MT
Built 1961 Load: 23.3 t ADT: 50
I 90
PoorOver: INT RESERVE STREET
MISSOULA, Missoula, MT
Built 1966 Load: 25.4 t ADT: 13,266
US 12 FH 11
PoorOver: LOLO CREEK
LOLO HOT SPRINGS, Missoula, MT
Built 1957 Load: 25.4 t ADT: 747
I 90
PoorOver: CLARK FORK RIVER
6.2M E ALBERTON, Missoula, MT
Built 1964 Load: 28.1 t ADT: 9,050
HWY 10 W
PoorOver: NINEMILE SLIDE 026
3M W HUSON, Missoula, MT
Built 1947 Load: 29.9 t ADT: 140
FINLEY CR RD
PoorOver: PLACID CR
FINLEY CR, Missoula, MT
Built 1959 Load: 30.5 t ADT: 50
TURAH RD
PoorOver: CLARK FORK 103
4M SE BONNER, Missoula, MT
Built 1962 Load: 31.8 t ADT: 100
HWY 10 W
PoorOver: NINEMILE CREEK 035
3M W HUSON, Missoula, MT
Built 1924 Load: 32.7 t ADT: 140
LOLO ST
PoorOver: RATTLESNAKE CREEK 009
MISSOULA-LOLO STREET, Missoula, MT
Built 1966 Load: 32.7 t ADT: 2,349
PLACID LAKE RD
PoorOver: OWL CREEK 077
3M S SEELEY LAKE, Missoula, MT
Built 1970 Load: 35.7 t ADT: 100
MULLAN RD
PoorOver: IRRIGATION CANAL
6M SE FRENCHTOWN, Missoula, MT
Built 1970 Load: 43.5 t ADT: 1,605
Read our methodology - how this data is sourced, computed, and verified.
Related
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.