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.
All bridges (158)
PIONEER ROAD
FairOver: COYOTE CREEK
4 MILES SOUTHWEST OF DENT, Fergus, MT
Built 1979 Load: 7.3 t ADT: 100
ARMELLS ROAD
FairOver: ARMELLS CREEK
11M NE HILGER, Fergus, MT
Built 2022 Load: 8.2 t ADT: 100
2ND AVENUE
FairOver: BIG SPRING CREEK 060
LEWISTOWN-2ND AVE, Fergus, MT
Built 1930 Load: 9.9 t ADT: 100
POOR FARM LOOP
FairOver: BIG SPRING CREEK
1M NW Lewistown, Fergus, MT
Built 1908 Load: 10.0 t ADT: 100
72 BENCH RD
FairOver: WARM SPRINGS CREEK 078
5M N DANVERS, Fergus, MT
Built 1980 Load: 10.0 t ADT: 100
FOREST GROVE RD
FairOver: S FORK MCDONALD CR 070
4M SW GRASSRANGE, Fergus, MT
Built 1982 Load: 10.0 t ADT: 146
SINGLE PINE RD
FairOver: COTTONWOOD CREEK 028
7M SW LEWISTOWN, Fergus, MT
Built 1989 Load: 10.0 t ADT: 100
BALLY DOME RD
FairOver: WOLF CREEK 089
7M E DENTON, Fergus, MT
Built 1979 Load: 11.8 t ADT: 100
VALENTINE RD
FairOver: BOX ELDER CREEK 130
8M E ROY, Fergus, MT
Built 1983 Load: 11.8 t ADT: 100
FOREST GROVE RD
FairOver: S FORK MCDONALD CR 046
6M SW GRASSRANGE, Fergus, MT
Built 1986 Load: 11.8 t ADT: 146
ALTON CUTOFF
FairOver: WOLF CREEK 091
4M E DENTON, Fergus, MT
Built 1979 Load: 12.7 t ADT: 100
ARNTZEN LN
FairOver: DOG CREEK
2M SE CHRISTINA, Fergus, MT
Built 2020 Load: 14.5 t ADT: 100
PACER COULEE RD
FairOver: DRY WOLF CREEK 093
4M SE DENTON, Fergus, MT
Built 1990 Load: 14.5 t ADT: 100
TYLER CUTOFF
FairOver: MCDONALD CREEK 125
1M S GRASSRANGE, Fergus, MT
Built 1975 Load: 15.4 t ADT: 100
US 87-E MAIN ST
FairOver: MILL DITCH
LEWISTOWN-E MAIN ST, Fergus, MT
Built 1922 Load: 15.4 t ADT: 8,688
W BRASSEY ST
FairOver: BIG SPRING CREEK
LEWISTOWN-W BRASSEY ST, Fergus, MT
Built 1920 Load: 15.4 t ADT: 1,899
NFSR #275
FairOver: ROCK CREEK
3 MI. N. OF CRYSTAL LAKE, Fergus, MT
Built 1938 Load: 15.9 t ADT: 50
N DENTON RD
FairOver: COFFEE CREEK 081
6M N DENTON, Fergus, MT
Built 1979 Load: 16.3 t ADT: 100
NFSR #275
FairOver: ROCK CREEK
5 MI NORTH OF CRYSTAL LK, Fergus, MT
Built 1954 Load: 16.5 t ADT: 50
OLIES RD
FairOver: WOLF CREEK 088
6M E DENTON, Fergus, MT
Built 1983 Load: 16.8 t ADT: 100
ERLE LN
FairOver: DOG CREEK 102
SUFFOLK, Fergus, MT
Built 1981 Load: 17.2 t ADT: 100
HITCHCOCK RD
FairOver: DRY WOLF CREEK 096
6M SE DENTON, Fergus, MT
Built 1980 Load: 17.7 t ADT: 4
BEAR SPRINGS RD
FairOver: WOLF CREEK 013
11M NE DENTON, Fergus, MT
Built 1980 Load: 18.1 t ADT: 13
CUNNINGHAM RD
FairOver: DRY WOLF CREEK 094
6M S DENTON, Fergus, MT
Built 1982 Load: 18.1 t ADT: 100
MILLER STREET
FairOver: MILL DITCH 041
LEWISTOWN-MILLER ST, Fergus, MT
Built 1973 Load: 18.1 t ADT: 100
WILDER TRAIL
FairOver: SACAGAWEA RIV 113
11M NE ROY, Fergus, MT
Built 2015 Load: 19.1 t ADT: 100
VALENTINE RD
FairOver: BLOOD CREEK 131
4M NW VALENTINE, Fergus, MT
Built 1980 Load: 19.1 t ADT: 100
FOREST GROVE RD
FairOver: S FORK MCDONALD CR 071
4M SW GRASSRANGE, Fergus, MT
Built 1970 Load: 19.1 t ADT: 146
US 87
FairOver: IRRIGATION RESERVOIR
6M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 19.1 t ADT: 1,300
S 81
FairOver: COFFEE CREEK
COFFEE CREEK, Fergus, MT
Built 1952 Load: 19.1 t ADT: 345
WATER STREET
FairOver: BIG SPRING CREEK 059
LEWISTOWN-WATER ST, Fergus, MT
Built 1930 Load: 20.8 t ADT: 100
COUNTY ROAD 116
FairOver: ARMELLS CREEK 115
10M NE HILGER, Fergus, MT
Built 1977 Load: 20.9 t ADT: 100
GRINDE RD
FairOver: WARM SPRINGS CREEK 009
4M SW HILGER, Fergus, MT
Built 1986 Load: 20.9 t ADT: 100
U BET RD
FairOver: ROSS FORK CREEK 026
W GARNEILL, Fergus, MT
Built 1987 Load: 20.9 t ADT: 36
UPPER SPRING CR RD
FairOver: MILL DITCH
LEWISTOWN, Fergus, MT
Built 1958 Load: 20.9 t ADT: 6,241
E BOULEVARD ST
FairOver: BIG SPRING CREEK
LEWISTOWN-E BOULEVARD ST, Fergus, MT
Built 1920 Load: 20.9 t ADT: 671
WASHBOARD RD
FairOver: DOG CREEK 101
W SUFFOLK, Fergus, MT
Built 1983 Load: 21.8 t ADT: 100
UPPER CHIPPEWA RD
FairOver: CHIPPEWA CREEK 004
5M NW GRASSRANGE, Fergus, MT
Built 1980 Load: 21.8 t ADT: 100
JENNI RD
FairOver: BEAVER CREEK 030
7M W LEWISTOWN, Fergus, MT
Built 1929 Load: 21.8 t ADT: 100
US 87
FairOver: S FORK MCDONALD CREEK
1M N GRASS RANGE, Fergus, MT
Built 1939 Load: 21.8 t ADT: 1,300
ROSE CREEK RD
FairOver: ROSE CREEK 108
3M E WINIFRED, Fergus, MT
Built 1980 Load: 22.7 t ADT: 100
S FORK RD
FairOver: FLATWILLOW CREEK 124
14M SE FORESTGROVE, Fergus, MT
Built 1986 Load: 22.7 t ADT: 100
GRAVES RD
FairOver: FLATWILLOW CREEK 001
20M S GRASSRANGE, Fergus, MT
Built 1988 Load: 22.7 t ADT: 100
US 87
FairOver: N FORK MCDONALD CREEK
8M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 22.7 t ADT: 1,300
US 87
FairOver: DRAINAGE
2M NW GRASS RANGE, Fergus, MT
Built 1939 Load: 22.7 t ADT: 1,300
VALENTINE RD
FairOver: BLOOD CREEK 132
25M N WINNETT, Fergus, MT
Built 1986 Load: 23.6 t ADT: 100
LWR COTTONWOOD CR
FairOver: COTTONWOOD CREEK 034
8M W LEWISTOWN, Fergus, MT
Built 2009 Load: 23.6 t ADT: 26
US 191-KENDALL RD
FairOver: BIG SPRING CREEK
LEWISTOWN-KENDALL RD, Fergus, MT
Built 1976 Load: 23.6 t ADT: 3,046
US 87
FairOver: BOYD CREEK
3M E LEWISTOWN, Fergus, MT
Built 1942 Load: 23.6 t ADT: 1,477
SURENUFF RD
FairOver: S FORK MCDONALD CR 002
FOREST GROVE, Fergus, MT
Built 1982 Load: 24.5 t ADT: 100
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.