County profile · official public datasets

Blaine County, MT

102 public highway bridges tracked in the FHWA National Bridge Inventory: 33.3% rated Good, 56.9% Fair, 9.8% Poor.

102
Public bridges
33.3%
Good condition
9.8%
Poor condition

The verdict

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

Blaine County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

44th
of 56 on Poor share
9.8%
Poor-condition share
102
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.

Blaine County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Blaine County ranks #44 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.8%). Blaine County, Montana contains 102 public highway bridges. Roughly 33.3% are rated “Good,” 56.9% “Fair,” and 9.8% “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

102

Public highway bridges in Blaine County

Good condition

33.3%

34 of 102 rated 7-9

Fair condition

56.9%

58 of 102 rated 5-6

Poor condition

9.8%

10 of 102 rated 4 or below

In-state Poor-share rank

#44 of 56

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

Condition distribution

Share of 102 NBI-tracked bridges by lowest applicable component rating.

Good
33.3% (34)
Fair
56.9% (58)
Poor
9.8% (10)

Blaine County's Poor-condition bridges carry 12,603 vehicle crossings a day

That is 18.9% of the county's reported daily bridge traffic on 9.8% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 1,260 crossings a day against 687 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 102 of 102 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

59.8% of Blaine County's bridges have passed the 50-year mark

61 of the 102 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 33.3% 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 25.4% of the county's Poor-condition bridge traffic

IRR - US 2 over MILK RIVER, built 1964, carries 3,196 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 12,603 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Blaine County's bridges were built

102 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1940s, when 20 of the county's bridges still in the inventory were built, which is 19.6% of those with a recorded year. That cohort is now 75 to 84 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 Blaine County compares with Montana's closest counties by inventory size

The 5 Montana counties nearest Blaine County in number of bridges, with their condition splits. Its 9.8% Poor share is the 3rd-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1978 is 9 years older.

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

Bridge inventory size and condition shares for Blaine County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Valley County 104 12.5%
Blaine County (this page) 102 9.8%
Phillips County 101 16.8%
Madison County 97 11.3%
Richland County 97 3.1%
Pondera County 96 4.2%

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

Similar inventory size

Nearest county inventories outside MT (102 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 102 Good 34 Fair 58 Poor 10

Good-condition bridges (34)

SAGE RD

Good

Over: E FORK BATTLE CREEK 053

18M N CHINOOK, Blaine, MT

Built 1999 Load: 4.5 t ADT: 100

OLD HWY RD E

Good

Over: BATTLE CREEK 025

5M E CHINOOK, Blaine, MT

Built 1938 Load: 14.5 t ADT: 100

IRR - S 66

Good

Over: LITTLE PEOPLES CREEK

2M NW HAYS, Blaine, MT

Built 2015 Load: 20.0 t ADT: 971

IRR - S 66

Good

Over: LITTLE PEOPLES CREEK

4M NW HAYS, Blaine, MT

Built 2015 Load: 20.0 t ADT: 971

IRR - S 66

Good

Over: LITTLE PEOPLES CREEK

8M NW HAYS, Blaine, MT

Built 2015 Load: 20.0 t ADT: 971

8 MILE RD

Good

Over: HARLEM CANAL 077

5M SE ZURICH, Blaine, MT

Built 2004 Load: 23.6 t ADT: 100

N FORK RD

Good

Over: MILK RIVER 036

4M W ZURICH, Blaine, MT

Built 2018 Load: 24.5 t ADT: 28

NEW HOPE RD

Good

Over: SNAKE CREEK 043

8M W HARLEM, Blaine, MT

Built 1987 Load: 24.5 t ADT: 100

COUNTY ROAD 007

Good

Over: MILK RIVER 014

1M N LOHMAN, Blaine, MT

Built 1997 Load: 26.3 t ADT: 125

US 2

Good

Over: BATTLE CREEK-N FK MILK R

3M W ZURICH, Blaine, MT

Built 1999 Load: 26.3 t ADT: 2,067

SAGE RD

Good

Over: BATTLE CREEK 052

15M N CHINOOK, Blaine, MT

Built 2009 Load: 26.9 t ADT: 100

TURNER RD

Good

Over: WOODY ISLAND CREEK

6M N TURNER, Blaine, MT

Built 1981 Load: 27.2 t ADT: 152

PARK RD

Good

Over: FIFTEEN MILE CREEK 020

1M N ZURICH, Blaine, MT

Built 1958 Load: 28.5 t ADT: 100

US 2

Good

Over: RED ROCK EAST OVERFLOW

1M W CHINOOK, Blaine, MT

Built 2020 Load: 29.0 t ADT: 2,637

ZURICH RD

Good

Over: MILK RIVER 033

S ZURICH, Blaine, MT

Built 1993 Load: 29.9 t ADT: 100

NEW HOPE RD

Good

Over: SNAKE CREEK 044

6M W HARLEM, Blaine, MT

Built 2004 Load: 30.1 t ADT: 100

S 396-SAVOY RD

Good

Over: SAVOY CREEK

2M SE SAVOY, Blaine, MT

Built 1990 Load: 30.8 t ADT: 5

IRR BIA RTE 134

Good

Over: LITTLE PEOPLES CREEK

4 KM SE OF HAYS, Blaine, MT

Built 2000 Load: 32.5 t ADT: 100

BAGAN RD

Good

Over: FORT BELKNAP CANAL 061

4M E CHINOOK, Blaine, MT

Built 2010 Load: 32.7 t ADT: 83

CHERRY RIDGE RD

Good

Over: FORT BELKNAP CANAL 066

1M W ZURICH, Blaine, MT

Built 2010 Load: 32.7 t ADT: 7

YANTIC RD

Good

Over: FORT BELKNAP CANAL 003

3M NE LOHMAN, Blaine, MT

Built 2012 Load: 32.7 t ADT: 40

S 325-ELLOAM RD

Good

Over: FORT BELKNAP CANAL

1M NE CHINOOK, Blaine, MT

Built 2012 Load: 32.7 t ADT: 213

IRR BIA RTE 19

Good

Over: PEOPLES CREEK

CHIPPEWA STREET IN HAYS, Blaine, MT

Built 2000 Load: 33.7 t ADT: 250

US 2

Good

Over: MAIN IRRIGATION CANAL

HARLEM, Blaine, MT

Built 1968 Load: 34.5 t ADT: 3,196

US 2

Good

Over: RED ROCK WEST OVERFLOW

2M W CHINOOK, Blaine, MT

Built 2020 Load: 35.4 t ADT: 2,637

VALLEY RD

Good

Over: MILK RIVER 125

12M E HARLEM, Blaine, MT

Built 2010 Load: 35.4 t ADT: 100

MERILL RD

Good

Over: MILK RIVER 081

4M W HARLEM, Blaine, MT

Built 2010 Load: 35.4 t ADT: 100

IRR - US 2

Good

Over: WHITE BEAR CREEK

11M W DODSON, Blaine, MT

Built 1993 Load: 38.1 t ADT: 1,281

IRR BIA RTE 37

Good

Over: LITTLE PEOPLES CREEK

AT ST PAULS MISSION, Blaine, MT

Built 2006 Load: 39.1 t ADT: 220

US 2

Good

Over: CLEAR CREEK

8M W CHINOOK, Blaine, MT

Built 2020 Load: 39.9 t ADT: 2,783

CLEVELAND RD

Good

Over: THREE MILE CREEK

2M S CHINOOK, Blaine, MT

Built 2014 Load: 40.8 t ADT: 849

US 2

Good

Over: RED ROCK COULEE

1M W CHINOOK, Blaine, MT

Built 2020 Load: 41.7 t ADT: 2,637

BAGAN RD

Good

Over: CORRAL COULEE 063

22M N CHINOOK, Blaine, MT

Built 2013 Load: 54.4 t ADT: 83

BARNEY OLSEN RD

Good

Over: PEOPLE`S CREEK 105

6M NE CLEVELAND, Blaine, MT

Built 2015 Load: 59.0 t ADT: 42

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.