Total bridges
94
Public highway bridges in Sweet Grass County
County profile · official public datasets
Sweet Grass County, MT
94 public highway bridges tracked in the FHWA National Bridge Inventory: 28.7% rated Good, 66% Fair, 5.3% Poor.
- 94
- Public bridges
- 28.7%
- Good condition
- 5.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Sweet Grass County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.
- Top 43%
- lowest Poor share in state
- 5.3%
- Poor-condition share
- 94
- public highway bridges
- 1977
- 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.
Sweet Grass County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Sweet Grass County ranks #24 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.3%). Sweet Grass County, Montana contains 94 public highway bridges. Roughly 28.7% are rated “Good,” 66% “Fair,” and 5.3% “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
28.7%
27 of 94 rated 7-9
Fair condition
66%
62 of 94 rated 5-6
Poor condition
5.3%
5 of 94 rated 4 or below
In-state Poor-share rank
#24 of 56
Among Montana counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 94 NBI-tracked bridges by lowest applicable component rating.
Good 28.7% (27)
Fair 66% (62)
Poor 5.3% (5)
Sweet Grass County's Poor-condition bridges carry 3,077 vehicle crossings a day
That is 1.5% of the county's reported daily bridge traffic on 5.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 615 crossings a day against 1,457 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 94 of 94 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
42.6% of Sweet Grass County's bridges have passed the 50-year mark
40 of the 94 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 28.7% 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 68.9% of the county's Poor-condition bridge traffic
S 91 over BOULDER RIVER OVERFLOW, built 1937, carries 2,120 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 5-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 3,077 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Sweet Grass County's bridges were built
94 bridges with a recorded construction year, grouped by decade
- 1910s 1
1910–1919
1 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s
1930–1939
9 bridges
- 1940s 3
1940–1949
3 bridges
- 1950s 2
1950–1959
2 bridges
- 1960s
1960–1969
9 bridges
- 1970s
1970–1979
20 bridges
- 1980s
1980–1989
22 bridges
- 1990s 5
1990–1999
5 bridges
- 2000s
2000–2009
10 bridges
- 2010s 6
2010–2019
6 bridges
- 2020s 5
2020–2029
5 bridges
What this shows Construction peaked in the 1980s, when 22 of the county's bridges still in the inventory were built, which is 23.4% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1977) matches the Montana average (1977).
How Sweet Grass County compares with Montana's closest counties by inventory size
The 5 Montana counties nearest Sweet Grass County in number of bridges, with their condition splits. Its 5.3% Poor share is the 4th-lowest of these 6. Its average build year of 1977 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 |
|---|---|---|---|---|---|
| Phillips County | 101 | 13.9% | 69.3% | 16.8% | 1972 |
| Madison County | 97 | 32% | 56.7% | 11.3% | 1981 |
| Richland County | 97 | 28.9% | 68% | 3.1% | 1988 |
| Pondera County | 96 | 51% | 44.8% | 4.2% | 1975 |
| Sweet Grass County (this page) | 94 | 28.7% | 66% | 5.3% | 1977 |
| Stillwater County | 92 | 30.4% | 68.5% | 1.1% | 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 Sweet Grass 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 Sweet Grass County, both outside Montana so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MT (94 bridges here).
- Yukon-Koyukuk County, AK · 94 bridges
- Lee County, AR · 94 bridges
- Huerfano County, CO · 94 bridges
- Henry County, KY · 94 bridges
Similar average build year
Nearest mean year-built outside MT (1977 here).
- San Diego County, CA · avg 1977 · 1,632 bridges
- King County, WA · avg 1977 · 1,238 bridges
- Riverside County, CA · avg 1977 · 1,117 bridges
- Shelby County, TN · avg 1977 · 1,077 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Good-condition bridges (27)
DRY FORK ROAD
GoodOver: E. BOULDER RIVER
NO DATA ENTERED, Sweet Grass, MT
Built 2007 Load: 16.8 t ADT: 50
OLD US 10
GoodOver: UPPER DEER CREEK 005
4M NW GREYCLIFF, Sweet Grass, MT
Built 1975 Load: 18.1 t ADT: 553
I 90
GoodOver: JARRETT CR FARM ACCESS
3.1M E SPRINGDALE, Sweet Grass, MT
Built 1981 Load: 23.6 t ADT: 6,078
I 90
GoodOver: CNTY RD 113-FRYER CREEK
4.3M E SPRINGDALE, Sweet Grass, MT
Built 1983 Load: 25.4 t ADT: 6,078
I 90
GoodOver: INT WEST BIG TIMBER
1.2M W BIG TIMBER, Sweet Grass, MT
Built 1981 Load: 26.3 t ADT: 6,078
NO DATA ENTERED
GoodOver: PICKET PIN CREEK
NO DATA ENTERED, Sweet Grass, MT
Built 2010 Load: 26.9 t ADT: 40
SOURDOUGH RD
GoodOver: SWEET GRASS CREEK 027
13M NE BIG TIMBER, Sweet Grass, MT
Built 1997 Load: 29.0 t ADT: 100
I 90
GoodOver: INT SPRINGDALE
SPRINGDALE, Sweet Grass, MT
Built 1981 Load: 30.8 t ADT: 6,078
I 90
GoodOver: INT SPRINGDALE
SPRINGDALE, Sweet Grass, MT
Built 1981 Load: 30.8 t ADT: 6,078
LOWER SWEET GRASS
GoodOver: SWEET GRASS CREEK 039
10M E BIG TIMBER, Sweet Grass, MT
Built 1965 Load: 30.8 t ADT: 100
LOWER SWEET GRASS
GoodOver: E FK SWEET GRASS CR 01
14M NE BIG TIMBER, Sweet Grass, MT
Built 2012 Load: 31.1 t ADT: 15
MELVILLE ROAD
GoodOver: SWEET GRASS CREEK
11 M NW MELVILLE, Sweet Grass, MT
Built 2023 Load: 32.1 t ADT: 100
OLD BOULDER ROAD
GoodOver: BOULDER RIVER 029
EAST BIG TIMBER, Sweet Grass, MT
Built 2020 Load: 32.7 t ADT: 100
I 90
GoodOver: LOWER DEER CREEK
0.6M W GREYCLIFF, Sweet Grass, MT
Built 1980 Load: 32.7 t ADT: 6,415
E BOULDER RD
GoodOver: BOULDER RIVER 030
2M S MCLEOD, Sweet Grass, MT
Built 2002 Load: 32.7 t ADT: 100
GLASTON RD
GoodOver: OTTER CREEK
7M SE MELVILLE, Sweet Grass, MT
Built 2013 Load: 33.6 t ADT: 65
BRIDGER CREEK ROAD
GoodOver: BRIDGER CREEK
9M SE GREYCLIFF, Sweet Grass, MT
Built 2022 Load: 33.6 t ADT: 100
HOWIE RD
GoodOver: OTTER CREEK
2M NE BIG TIMBER, Sweet Grass, MT
Built 2000 Load: 33.6 t ADT: 481
BOULDER RD
GoodOver: BOULDER RIVER 003
12M S MCLEOD, Sweet Grass, MT
Built 2017 Load: 34.5 t ADT: 156
BRIDGER CREEK RD
GoodOver: BRIDGER CREEK
13.6M SE GREYCLIFF, Sweet Grass, MT
Built 2021 Load: 34.5 t ADT: 100
OTTER CREEK RD
GoodOver: SWEET GRASS CREEK 00
6M SE MELVILLE, Sweet Grass, MT
Built 2009 Load: 34.5 t ADT: 65
WHEELER CREEK RD
GoodOver: WHEELER CREEK
3.3M W HWY 191, Sweet Grass, MT
Built 2007 Load: 35.4 t ADT: 100
SWAMP CREEK RD
GoodOver: BIG TIMBER CREEK
4M N BIG TIMBER, Sweet Grass, MT
Built 2019 Load: 35.4 t ADT: 100
LOWER SWEET GRASS
GoodOver: SWEET GRASS CREEK 01
12M NE BIG TIMBER, Sweet Grass, MT
Built 2017 Load: 37.2 t ADT: 15
RAPELJE RD
GoodOver: SWEET GRASS CREEK
11M NE BIG TIMBER, Sweet Grass, MT
Built 1993 Load: 38.1 t ADT: 57
SWAMP CREEK RD
GoodOver: SWAMP CREEK
5.9M N BIG TIMBER, Sweet Grass, MT
Built 2020 Load: 39.0 t ADT: 100
DERBY GULCH ROAD
GoodOver: WEST BRIDGER CREEK
NO DATA ENTERED, Sweet Grass, MT
Built 2007 Load: 42.8 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.