County profile · official public datasets

Cascade County, MT

185 public highway bridges tracked in the FHWA National Bridge Inventory: 41.6% rated Good, 54.6% Fair, 3.8% Poor.

185
Public bridges: 41.6%
Good condition: 3.8%
Poor condition

The verdict

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

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

Top 23%
lowest Poor share in state: 3.8%
Poor-condition share: 185
public highway bridges: 1965
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.

Cascade County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Cascade County ranks #13 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.8%). Cascade County, Montana contains 185 public highway bridges. Roughly 41.6% are rated “Good,” 54.6% “Fair,” and 3.8% “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

185

Public highway bridges in Cascade County

Good condition

41.6%

77 of 185 rated 7-9

Fair condition

54.6%

101 of 185 rated 5-6

Poor condition

3.8%

7 of 185 rated 4 or below

In-state Poor-share rank

#13 of 56

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

Condition distribution

Share of 185 NBI-tracked bridges by lowest applicable component rating.

Good

41.6% (77)

Fair

54.6% (101)

Poor

3.8% (7)

Cascade County's Poor-condition bridges carry 1,573 vehicle crossings a day

That is 0.4% of the county's reported daily bridge traffic on 3.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 225 crossings a day against 2,051 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 185 of 185 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

75.1% of Cascade County's bridges have passed the 50-year mark

139 of the 185 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 41.6% 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 72.7% of the county's Poor-condition bridge traffic

US 89 FH 32 over BELT CREEK, built 1968, carries 1,144 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 7-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,573 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

3
1910s

1
1920s

3
1930s

16
1940s

6
1950s

41
1960s

50
1970s

27
1980s

10
1990s

7
2000s

16
2010s

4
2020s

1

What this shows Construction peaked in the 1960s, when 50 of the county's bridges still in the inventory were built, which is 27% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1965, 12 years older than the Montana average of 1977.

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

The 5 Montana counties nearest Cascade County in number of bridges, with their condition splits. Its 3.8% Poor share is the 1st-lowest of these 6. Its average build year of 1965 against a peer-group mean of 1978 is 13 years older.

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

Bridge inventory size and condition shares for Cascade County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Gallatin County	210	19%	76.7%	4.3%	1977
Missoula County	206	33.5%	58.7%	7.8%	1976
Flathead County	204	30.9%	64.2%	4.9%	1983
Lewis and Clark County	200	58%	36.5%	5.5%	1979
Lincoln County	190	38.4%	46.8%	14.7%	1977
Cascade County (this page)	185	41.6%	54.6%	3.8%	1965

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

Similar inventory size

Nearest county inventories outside MT (185 bridges here).

Chambers County, AL · 185 bridges
Maui County, HI · 185 bridges
Lawrence County, IL · 185 bridges
Saline County, IL · 185 bridges

Similar average build year

Nearest mean year-built outside MT (1965 here).

Windsor County, VT · avg 1965 · 483 bridges
Bedford County, PA · avg 1965 · 417 bridges
Crawford County, PA · avg 1965 · 399 bridges
Harper County, KS · avg 1965 · 372 bridges

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

All 185 Good 77 Fair 101 Poor 7

Good-condition bridges (77)

Sort:

Cascade County Bridge Snapshot

Condition distribution

Cascade County's Poor-condition bridges carry 1,573 vehicle crossings a day

75.1% of Cascade County's bridges have passed the 50-year mark

One structure carries 72.7% of the county's Poor-condition bridge traffic

How Cascade 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

Good-condition bridges (77)

I 15

I 15

JARVI RD

SUN R CASCADE RD

CENTRAL AVE W

CENTRAL AVE

FDR 267

LOWREY RD

KLOCK RD

7TH LN

OLD ULM CASCADE RD

BLAINE ST

MILLEGAN RD

MILLEGAN RD

BRANCH I 15-U.S. 8

JOHNSON RD

BOSTON COULEE RD

OLD ULM CASCADE RD

N FORT SHAW RD

HUGHESVILLE RD

SIMMS FAIRFIELD RD

SALEM RD

I 15

I 15

US 89 FH 32

US 89 FH 32

US 89 FH 32

SIMMS CASCADE RD

US 89

US 89 FH 32

MEYER AVE

US 89

S 200

US 89 FH 32

I 15

WILLOW CREEK RD

I 315 S

OFF RAMP TO 14TH S

HUGHESVILLE RD

UPPER MILLEGAN RD

34TH ST NW

I 15

ULM VAUGHN RD

I 15

I 15

I 15

US 87-US 89

I 15

I 15

BRANCH I 15-U.S. 8

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