Total bridges
73
Public highway bridges in Granite County
County profile · official public datasets
Granite County, MT
73 public highway bridges tracked in the FHWA National Bridge Inventory: 37% rated Good, 52.1% Fair, 11% Poor.
- 73
- Public bridges
- 37%
- Good condition
- 11%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Granite County posts a higher-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.
- 47th
- of 56 on Poor share
- 11%
- Poor-condition share
- 73
- public highway bridges
- 1974
- 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.
Granite County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Granite County ranks #47 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 11%). Granite County, Montana contains 73 public highway bridges. Roughly 37% are rated “Good,” 52.1% “Fair,” and 11% “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
37%
27 of 73 rated 7-9
Fair condition
52.1%
38 of 73 rated 5-6
Poor condition
11%
8 of 73 rated 4 or below
In-state Poor-share rank
#47 of 56
Among Montana counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 73 NBI-tracked bridges by lowest applicable component rating.
Good 37% (27)
Fair 52.1% (38)
Poor 11% (8)
Granite County's Poor-condition bridges carry 14,360 vehicle crossings a day
That is 10.3% of the county's reported daily bridge traffic on 11% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,795 crossings a day against 2,189 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 73 of 73 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
61.6% of Granite County's bridges have passed the 50-year mark
45 of the 73 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 37% 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 83.4% of the county's Poor-condition bridge traffic
I 90 over CLARK FORK RIVER, built 1970, carries 11,980 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 8-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 14,360 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Granite County's bridges were built
73 bridges with a recorded construction year, grouped by decade
- 1930s 5
1930–1939
5 bridges
- 1940s 1
1940–1949
1 bridges
- 1950s 7
1950–1959
7 bridges
- 1960s
1960–1969
20 bridges
- 1970s
1970–1979
16 bridges
- 1980s
1980–1989
8 bridges
- 1990s 7
1990–1999
7 bridges
- 2000s 5
2000–2009
5 bridges
- 2010s 4
2010–2019
4 bridges
What this shows Construction peaked in the 1960s, when 20 of the county's bridges still in the inventory were built, which is 27.4% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1974) matches the Montana average (1977).
How Granite County compares with Montana's closest counties by inventory size
The 5 Montana counties nearest Granite County in number of bridges, with their condition splits. Its 11% Poor share is the 6th-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1976 is in line with the group.
Showing the 5 closest of 55 Montana counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Carbon County | 80 | 36.3% | 58.8% | 5% | 1985 |
| Granite County (this page) | 73 | 37% | 52.1% | 11% | 1974 |
| Custer County | 71 | 14.1% | 84.5% | 1.4% | 1969 |
| Glacier County | 71 | 38% | 56.3% | 5.6% | 1978 |
| Deer Lodge County | 68 | 27.9% | 66.2% | 5.9% | 1973 |
| Silver Bow County | 68 | 16.2% | 82.4% | 1.5% | 1974 |
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 Granite 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 Granite County, both outside Montana so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MT (73 bridges here).
- Stone County, AR · 73 bridges
- Levy County, FL · 73 bridges
- Putnam County, FL · 73 bridges
- Dade County, GA · 73 bridges
Similar average build year
Nearest mean year-built outside MT (1974 here).
- Knox County, TN · avg 1974 · 588 bridges
- Summit County, OH · avg 1974 · 563 bridges
- Onondaga County, NY · avg 1974 · 472 bridges
- Orange County, NY · avg 1974 · 472 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (38)
NO DATA ENTERED
FairOver: FLINT CREEK
5 MI. N. OF P-BURG ON HWY, Granite, MT
Built 2001 Load: 20.1 t ADT: 50
GRIZZLE CAMP RD
FairOver: RANCH CR
GRIZZLY CAMP, Granite, MT
Built 1958 Load: 20.1 t ADT: 50
UPPER ROCK CR RD
FairOver: STONY CREEK 011
19M W PHILLIPSBURG, Granite, MT
Built 1999 Load: 20.1 t ADT: 592
FRONTAGE ROAD 153
FairOver: CLARK FORK RIVER 034
14M W DRUMMOND, Granite, MT
Built 1970 Load: 20.1 t ADT: 267
NO DATA ENTERED
FairOver: HOGBACK CREEK
NO DATA ENTERED, Granite, MT
Built 2008 Load: 21.1 t ADT: 50
MANY GLACIER ROAD
FairOver: WINDY CREEK
8.8 miles west of U.S. Ro, Granite, MT
Built 1931 Load: 21.8 t ADT: 452
S 1
FairOver: FLINT CREEK
4M N MAXVILLE, Granite, MT
Built 1931 Load: 23.6 t ADT: 1,123
S 1
FairOver: FRED BURR CREEK
2M S PHILIPSBURG, Granite, MT
Built 1931 Load: 24.5 t ADT: 1,663
NO DATA ENTERED
FairOver: COPPER CR
AFTER COPPER CREEK CG, Granite, MT
Built 1956 Load: 24.6 t ADT: 50
I 90
FairOver: CLARK FORK RIVER
0.6M W BEARMOUTH, Granite, MT
Built 1970 Load: 25.4 t ADT: 11,108
S 1
FairOver: BOULDER CREEK
MAXVILLE, Granite, MT
Built 1986 Load: 25.4 t ADT: 1,123
NO DATA ENTERED
FairOver: MIDDLE FORK ROCK CR
AT JUNCTION TO MOOSE LAKE, Granite, MT
Built 1956 Load: 25.9 t ADT: 50
MULLAN RD E
FairOver: FLINT CREEK 001
2M S DRUMMOND, Granite, MT
Built 1998 Load: 26.3 t ADT: 100
GOLD COIN ROAD
FairOver: FLINT CREEK 017
13M S DRUMMOND, Granite, MT
Built 1984 Load: 26.3 t ADT: 100
MAIN ST
FairOver: BERGMAN SLOUGH 019
DRUMMOND-MAIN STREET, Granite, MT
Built 1934 Load: 29.9 t ADT: 544
S 1
FairOver: WILLOW CREEK
4M S DRUMMOND, Granite, MT
Built 1999 Load: 29.9 t ADT: 1,260
NO DATA ENTERED
FairOver: ROSS FORK
ROSS FORK, Granite, MT
Built 1962 Load: 30.5 t ADT: 50
NO DATA ENTERED
FairOver: SPILLWAY
SPILLWAY, Granite, MT
Built 1958 Load: 30.8 t ADT: 50
NO DATA ENTERED
FairOver: MIDDLE FORK ROCK CR
MIDDLE FORK ROCK CR, Granite, MT
Built 1965 Load: 31.1 t ADT: 40
NO DATA ENTERED
FairOver: WEST FORK ROCK CR
WEST FORK ROCK CR, Granite, MT
Built 1965 Load: 32.7 t ADT: 50
I 90
FairOver: SEP BEARMOUTH ROAD
10.5M W DRUMMOND, Granite, MT
Built 1970 Load: 32.7 t ADT: 11,980
I 90
FairOver: INT E DRUMMOND
DRUMMOND, Granite, MT
Built 1966 Load: 32.7 t ADT: 5,104
I 90
FairOver: INT E DRUMMOND
DRUMMOND, Granite, MT
Built 1966 Load: 32.7 t ADT: 5,104
S 1
FairOver: ABANDONED RAILROAD
DRUMMOND, Granite, MT
Built 1966 Load: 32.7 t ADT: 1,329
NO DATA ENTERED
FairOver: GOLD CREEK
JACKSON PARK ROAD, Granite, MT
Built 1975 Load: 33.0 t ADT: 40
NO DATA ENTERED
FairOver: ROSS FORK
ROSS FORK, Granite, MT
Built 1961 Load: 34.0 t ADT: 40
I 90
FairOver: INT W DRUMMOND
DRUMMOND, Granite, MT
Built 1966 Load: 34.5 t ADT: 5,990
I 90
FairOver: INT W DRUMMOND
DRUMMOND, Granite, MT
Built 1966 Load: 34.5 t ADT: 4,305
NO DATA ENTERED
FairOver: MIDDLE FORK ROCK CR
BEFORE KAISER LAKE, Granite, MT
Built 1965 Load: 35.0 t ADT: 40
NO DATA ENTERED
FairOver: WEST FORK ROCK CR
WEST FORK ROCK CR, Granite, MT
Built 1969 Load: 35.3 t ADT: 40
NO DATA ENTERED
FairOver: BOWLES CR
BOWLES CR, Granite, MT
Built 1971 Load: 35.3 t ADT: 50
I 90
FairOver: SEP S-271
1.2M E DRUMMOND, Granite, MT
Built 1966 Load: 35.4 t ADT: 5,104
S 1
FairOver: RR
DRUMMOND, Granite, MT
Built 1966 Load: 35.4 t ADT: 1,329
NO DATA ENTERED
FairOver: ROSS FORK
ROSS FORK, Granite, MT
Built 1967 Load: 35.6 t ADT: 50
I 90
FairOver: INT BEARMOUTH
BEARMOUTH, Granite, MT
Built 1970 Load: 35.6 t ADT: 5,554
MARSHALL CREEK RD
FairOver: FLINT CREEK
1M W PHILIPSBURG, Granite, MT
Built 1956 Load: 37.2 t ADT: 345
ROCK CREEK RD
FairOver: RANCH CREEK 009
10M S ROCK CREEK INT, Granite, MT
Built 1977 Load: 38.1 t ADT: 592
ROAD 5156
FairOver: UPPER WILLOW CR
UPPER WILLOW CR, Granite, MT
Built 1968 Load: 42.1 t ADT: 40
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.