County profile · official public datasets

Custer County, MT

71 public highway bridges tracked in the FHWA National Bridge Inventory: 14.1% rated Good, 84.5% Fair, 1.4% Poor.

71
Public bridges
14.1%
Good condition
1.4%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Custer County pairs a top-10% lowest Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 9%
lowest Poor share in state
1.4%
Poor-condition share
71
public highway bridges
1969
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.

Custer County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Custer County ranks #5 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1.4%). Custer County, Montana contains 71 public highway bridges. Roughly 14.1% are rated “Good,” 84.5% “Fair,” and 1.4% “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.

Total bridges

71

Public highway bridges in Custer County

Good condition

14.1%

10 of 71 rated 7-9

Fair condition

84.5%

60 of 71 rated 5-6

Poor condition

1.4%

1 of 71 rated 4 or below

In-state Poor-share rank

#5 of 56

Among Montana counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 71 NBI-tracked bridges by lowest applicable component rating.

Good
14.1% (10)
Fair
84.5% (60)
Poor
1.4% (1)

Custer County's Poor-condition bridges carry 100 vehicle crossings a day

That is 0.1% of the county's reported daily bridge traffic on 1.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 100 crossings a day against 1,105 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 71 of 71 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

60.6% of Custer County's bridges have passed the 50-year mark

43 of the 71 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 14.1% 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 100% of the county's Poor-condition bridge traffic

FRONTAGE ROAD 205 over SNELL CREEK 073, built 1928, carries 100 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 1-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 100 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Custer County's bridges were built

71 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 13 of the county's bridges still in the inventory were built, which is 18.3% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1969, 8 years older than the Montana average of 1977.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Custer County compares with Montana's closest counties by inventory size

The 5 Montana counties nearest Custer County in number of bridges, with their condition splits. Its 1.4% Poor share is the 1st-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1976 is 7 years older.

Showing the 5 closest of 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Custer County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Granite County 73 11%
Glacier County 71 5.6%
Custer County (this page) 71 1.4%
Deer Lodge County 68 5.9%
Silver Bow County 68 1.5%
Sheridan County 66 3%

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 Custer 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 Custer County, both outside Montana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MT (71 bridges here).

Similar average build year

Nearest mean year-built outside MT (1969 here).

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 71 Good 10 Fair 60 Poor 1

All bridges (71)

I 94

Fair

Over: TONGUE RIVER

1M S MILES CITY, Custer, MT

Built 1961 Load: 41.7 t ADT: 4,570

POWDERVILLE RD

Fair

Over: PUMPKIN CREEK 002

31M S MILES CITY, Custer, MT

Built 1981 Load: 43.5 t ADT: 47

TRAIL CREEK RD

Fair

Over: MIZPAH CREEK 086

27M SE MILES CITY, Custer, MT

Built 1981 Load: 47.2 t ADT: 56

I 94

Fair

Over: INT DIAMOND RING

21M NE MILES CITY, Custer, MT

Built 1971 Load: 51.7 t ADT: 2,110

LOWER RD

Fair

Over: MUSTER CREEK 001

1M SW KINSEY, Custer, MT

Built 1994 Load: 51.7 t ADT: 100

S 59

Fair

Over: PUMPKIN CREEK

14M SE MILES CITY, Custer, MT

Built 1962 Load: 53.5 t ADT: 673

I 94

Fair

Over: LIGNITE CREEK

8M SW MILES CITY, Custer, MT

Built 1964 Load: 89.8 t ADT: 4,646

I 94

Fair

Over: COAL CREEK

7M SW MILES CITY, Custer, MT

Built 1963 Load: 89.8 t ADT: 4,646

S 59

Fair

Over: MILL CREEK-STOCKPASS

7M SE MILES CITY, Custer, MT

Built 1986 Load: 89.8 t ADT: 952

I 94

Fair

Over: JONES CREEK-STOCKPASS

8M NE MILES CITY, Custer, MT

Built 1962 Load: 99.9 t ADT: 4,494

SHEEP CREEK RD

Good

Over: SHEEP CREEK

36M E MILES CITY, Custer, MT

Built 2023 ADT: 22

FRONTAGE ROAD 005

Good

Over: MOON CREEK 093

9M SW MILES CITY, Custer, MT

Built 2013 Load: 18.1 t ADT: 100

I 94

Good

Over: INT P-23 BROADUS

SE EDGE MILES CITY, Custer, MT

Built 2019 Load: 25.4 t ADT: 2,285

I 94

Good

Over: INT P-23 BROADUS

SE EDGE MILES CITY, Custer, MT

Built 2020 Load: 25.4 t ADT: 2,285

WHITNEY CR RD

Good

Over: O`FALLON CREEK

ISMAY-WHITNEY CR RD, Custer, MT

Built 1990 Load: 28.1 t ADT: 38

US 12

Good

Over: BENSLEY CREEK

6M E MILES CITY, Custer, MT

Built 1999 Load: 30.8 t ADT: 643

TRAIL CREEK RD

Good

Over: MASON CREEK 059

49M E MILES CITY, Custer, MT

Built 2016 Load: 36.3 t ADT: 100

TRAIL CREEK RD

Good

Over: STREVELL CREEK 042

25M SE MILES CITY, Custer, MT

Built 2018 Load: 39.9 t ADT: 56

S 59

Good

Over: NORTH WOMAN CREEK

9M SE MILES CITY, Custer, MT

Built 1986 Load: 89.8 t ADT: 952

I 94

Good

Over: VEHICLE PASS

13M NE MILES CITY, Custer, MT

Built 1986 Load: 99.9 t ADT: 4,570

FRONTAGE ROAD 205

Poor

Over: SNELL CREEK 073

17M SW MILES CITY, Custer, MT

Built 1928 Load: 20.9 t ADT: 100

Read our methodology - how this data is sourced, computed, and verified.

Related

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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.