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

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.

1900s

2
1910s

2
1920s

7
1930s

3
1950s

4
1960s

13
1970s

13
1980s

13
1990s

3
2000s

4
2010s

5
2020s

2

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.

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	Good	Fair	Poor	Avg. built
Granite County	73	37%	52.1%	11%	1974
Glacier County	71	38%	56.3%	5.6%	1978
Custer County (this page)	71	14.1%	84.5%	1.4%	1969
Deer Lodge County	68	27.9%	66.2%	5.9%	1973
Silver Bow County	68	16.2%	82.4%	1.5%	1974
Sheridan County	66	16.7%	80.3%	3%	1979

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).

Rio Grande County, CO · 71 bridges
Charlton County, GA · 71 bridges
Madison County, GA · 71 bridges
Taylor County, GA · 71 bridges

Similar average build year

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

Cook County, IL · avg 1969 · 1,721 bridges
Fresno County, CA · avg 1969 · 916 bridges
Cuyahoga County, OH · avg 1969 · 871 bridges
Ventura County, CA · avg 1969 · 501 bridges

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)

Sort:

Custer County Bridge Snapshot

Condition distribution

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

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

One structure carries 100% of the county's Poor-condition bridge traffic

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

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (71)

CEMETARY RD

DEADMAN RD

TRAIL CREEK RD

TUSLER RD

FRONTAGE ROAD 201

POWDERVILLE RD

S 59

S 332

N LOCATE RD

FRNTAGE ROAD 81020

KIRCHER CREEK RD

POWDERVILLE RD

MOON CREEK RD

S 332

FRNTAGE ROAD 81020

US 94

S 59

S 59

I 94

I 94

I 94

I 94

VALLEY DR E

CROW ROCK RD

POWDERVILLE RD

US 94

US 12

I 94

I 94

MOON CREEK RD

FRONTAGE ROAD 205

FRONTAGE ROAD 005

S 59

I 94

I 94

COUNTY ROAD 214

SIGNAL BUTTE RD

FRNTAGE ROAD 81020

US 94

POWDER RIVER RD

COUNTY ROAD 304

S 59

I 94

S 489

I 94

WYTTENHOVE LN

PACIFIC AVE

US 94

I 94

I 94

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