Total bridges
158
Public highway bridges in Fergus County
County profile · official public datasets
Fergus County, MT
158 public highway bridges tracked in the FHWA National Bridge Inventory: 31.6% rated Good, 62% Fair, 6.3% Poor.
- 158
- Public bridges
- 31.6%
- Good condition
- 6.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Fergus County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 31st
- of 56 on Poor share
- 6.3%
- Poor-condition share
- 158
- public highway bridges
- 1978
- 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.
Fergus County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Fergus County ranks #31 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). Fergus County, Montana contains 158 public highway bridges. Roughly 31.6% are rated “Good,” 62% “Fair,” and 6.3% “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
31.6%
50 of 158 rated 7-9
Fair condition
62%
98 of 158 rated 5-6
Poor condition
6.3%
10 of 158 rated 4 or below
In-state Poor-share rank
#31 of 56
Among Montana counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 158 NBI-tracked bridges by lowest applicable component rating.
Good 31.6% (50)
Fair 62% (98)
Poor 6.3% (10)
Fergus County's Poor-condition bridges carry 3,802 vehicle crossings a day
That is 4% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 380 crossings a day against 449 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 158 of 158 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
44.9% of Fergus County's bridges have passed the 50-year mark
71 of the 158 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 31.6% 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 37.9% of the county's Poor-condition bridge traffic
US 87 over DRAINAGE, built 1939, carries 1,442 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 10-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 3,802 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Fergus County's bridges were built
158 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1920s 4
1920–1929
4 bridges
- 1930s
1930–1939
16 bridges
- 1940s 9
1940–1949
9 bridges
- 1950s 10
1950–1959
10 bridges
- 1960s
1960–1969
27 bridges
- 1970s
1970–1979
15 bridges
- 1980s
1980–1989
25 bridges
- 1990s 7
1990–1999
7 bridges
- 2000s 9
2000–2009
9 bridges
- 2010s
2010–2019
18 bridges
- 2020s
2020–2029
17 bridges
What this shows Construction peaked in the 1960s, when 27 of the county's bridges still in the inventory were built, which is 17.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1978) matches the Montana average (1977).
How Fergus County compares with Montana's closest counties by inventory size
The 5 Montana counties nearest Fergus County in number of bridges, with their condition splits. Its 6.3% Poor share is the 5th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1974 is in line with the group.
Showing the 5 closest of 55 Montana counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Cascade County | 185 | 41.6% | 54.6% | 3.8% | 1965 |
| Fergus County (this page) | 158 | 31.6% | 62% | 6.3% | 1978 |
| Mineral County | 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 |
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 Fergus 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 Fergus County, both outside Montana so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MT (158 bridges here).
- Napa County, CA · 158 bridges
- Wells County, IN · 158 bridges
- Jackson County, MI · 158 bridges
- Yalobusha County, MS · 158 bridges
Similar average build year
Nearest mean year-built outside MT (1978 here).
- Orange County, CA · avg 1978 · 1,164 bridges
- Sumner County, KS · avg 1978 · 659 bridges
- Allen County, IN · avg 1978 · 613 bridges
- Livingston County, IL · avg 1978 · 579 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (98)
US 87
FairOver: DRAINAGE
12M E LEWISTOWN, Fergus, MT
Built 1930 Load: 24.5 t ADT: 1,442
S 80
FairOver: ARROW CREEK
17M S GERALDINE, Fergus, MT
Built 1949 Load: 24.5 t ADT: 170
HANOVER RD
FairOver: JUDITH RIVER
5M NE KOLIN, Fergus, MT
Built 1970 Load: 24.5 t ADT: 113
FISH HATCHERY RD
FairOver: E FORK BIG SPRING CREEK
4M SE LEWISTOWN, Fergus, MT
Built 1966 Load: 24.5 t ADT: 161
WINIFRED HWY
FairOver: DOG CREEK
4M N HILGER, Fergus, MT
Built 1953 Load: 25.4 t ADT: 474
WINIFRED HWY
FairOver: DRAINAGE
3M S CHRISTINA, Fergus, MT
Built 1954 Load: 25.4 t ADT: 474
WINIFRED HWY
FairOver: DOG CREEK
CHRISTINA, Fergus, MT
Built 1954 Load: 25.4 t ADT: 474
US 191-1ST AVE N
FairOver: BIG SPRING CREEK
LEWISTOWN-1ST AVE N, Fergus, MT
Built 1960 Load: 26.3 t ADT: 6,387
US 87
FairOver: DRAINAGE
10M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 26.3 t ADT: 1,442
HANOVER RD
FairOver: BIG SPRING CREEK
8M NW LEWISTOWN, Fergus, MT
Built 1966 Load: 26.3 t ADT: 1
DONALDSON RD
FairOver: DRY WOLF CREEK 090
7M E DENTON, Fergus, MT
Built 1982 Load: 27.2 t ADT: 100
UPPER ELK CR RD
FairOver: ELK CREEK 126
6M S GRASSRANGE, Fergus, MT
Built 1982 Load: 27.2 t ADT: 100
US 87
FairOver: DRAINAGE
6M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 27.2 t ADT: 1,300
US 87
FairOver: DRAINAGE
3M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 27.2 t ADT: 1,300
S 81
FairOver: DRY WOLF CREEK
6M SE DENTON, Fergus, MT
Built 1949 Load: 27.2 t ADT: 263
COUNTY ROAD 220
FairOver: FORDS CREEK 006
14M NW GRASSRANGE, Fergus, MT
Built 1981 Load: 28.1 t ADT: 100
US 191
FairOver: ARMELLS CREEK
27M NE ROY, Fergus, MT
Built 1963 Load: 28.1 t ADT: 622
SALT CREEK RD
FairOver: SALT CREEK 053
7M NW SUFFOLK, Fergus, MT
Built 1984 Load: 29.0 t ADT: 100
US 191
FairOver: BOX ELDER CREEK
2M E ROY, Fergus, MT
Built 1942 Load: 29.0 t ADT: 287
US 87
FairOver: DRAINAGE
7M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 29.0 t ADT: 1,300
US 87
FairOver: DRAINAGE
4M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 29.0 t ADT: 1,300
US 87
FairOver: DRAINAGE
2M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 29.0 t ADT: 1,300
HITCHCOCK RD
FairOver: DRY WOLF CREEK 095
5M SE DENTON, Fergus, MT
Built 1980 Load: 29.3 t ADT: 4
BUTCHER RD
FairOver: DOG CREEK 107
4M S WINIFRED, Fergus, MT
Built 1962 Load: 29.9 t ADT: 100
US 87-W MAIN ST
FairOver: BIG SPRING CREEK
LEWISTOWN-W MAIN ST, Fergus, MT
Built 1962 Load: 29.9 t ADT: 5,247
US 87
FairOver: ELK CREEK
5M SE GRASS RANGE, Fergus, MT
Built 1952 Load: 29.9 t ADT: 1,038
LOWER RD
FairOver: WOLF CREEK 086
5M SW DENTON, Fergus, MT
Built 1962 Load: 30.8 t ADT: 73
US 87
FairOver: COTTONWOOD CREEK
5M SW LEWISTOWN, Fergus, MT
Built 2009 Load: 30.8 t ADT: 2,443
S 81
FairOver: WARM SPRING CREEK
7M SW HILGER, Fergus, MT
Built 1949 Load: 30.8 t ADT: 375
S 81
FairOver: WARM SPRING CREEK
5M SW HILGER, Fergus, MT
Built 1969 Load: 30.8 t ADT: 375
S COFFEE CR RD
FairOver: WOLF CREEK 076
4M S COFFEE CREEK, Fergus, MT
Built 1979 Load: 31.1 t ADT: 34
US 87
FairOver: BOYD CREEK
1M E LEWISTOWN, Fergus, MT
Built 1942 Load: 31.8 t ADT: 2,908
DY TRAIL
FairOver: DOG CREEK 110
E WINIFRED, Fergus, MT
Built 1962 Load: 32.7 t ADT: 167
TOGNETTI RD
FairOver: ROSS FORK 038
5M NW MOORE, Fergus, MT
Built 1995 Load: 32.7 t ADT: 100
CRABTREE RD
FairOver: DRY WOLF CREEK 092
5M SE DENTON, Fergus, MT
Built 1962 Load: 32.7 t ADT: 100
PINE STREET
FairOver: BIG SPRING CREEK 058
LEWISTOWN-PINE ST, Fergus, MT
Built 1962 Load: 32.7 t ADT: 100
S 238-E FORK RD
FairOver: E FORK BIG SPRING CREEK
8M SE LEWISTOWN, Fergus, MT
Built 1958 Load: 32.7 t ADT: 216
SW ASH ST
FairOver: BIG SPRING CREEK
LEWISTOWN-SW ASH ST, Fergus, MT
Built 1962 Load: 32.7 t ADT: 1,386
3 MILE RD
FairOver: SALT CREEK 055
6M W SUFFOLK, Fergus, MT
Built 1962 Load: 33.5 t ADT: 100
US 191
FairOver: WARM SPRINGS CREEK
5M SW HILGER, Fergus, MT
Built 2011 Load: 34.5 t ADT: 841
WINIFRED HWY
FairOver: DOG CREEK
CHRISTINA, Fergus, MT
Built 1954 Load: 34.5 t ADT: 382
SERIGHT RD
FairOver: ROCK CREEK 045
3M E MOORE, Fergus, MT
Built 1962 Load: 35.3 t ADT: 100
CIMRHAKL RD
FairOver: SACAGAWEA RIV 114
8M NE ROY, Fergus, MT
Built 1978 Load: 35.4 t ADT: 100
YELLOW WATER RD
FairOver: ELK CREEK 136
7 M SE GRASSRANGE, Fergus, MT
Built 1974 Load: 36.5 t ADT: 100
SALT CREEK RD
FairOver: DOG CREEK 054
N SUFFOLK, Fergus, MT
Built 1962 Load: 37.1 t ADT: 100
LOWER RD
FairOver: COYOTE CREEK 085
1M SW DENTON, Fergus, MT
Built 1977 Load: 59.1 t ADT: 73
UPPER CHIPPEWA RD
FairOver: CHIPPEWA CREEK 021
8M NW GRASSRANGE, Fergus, MT
Built 1962 Load: 99.9 t ADT: 100
US 191
FairOver: ROSS FORK CREEK
2M N JUDITH GAP, Fergus, MT
Built 1990 Load: 99.9 t ADT: 2,077
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.