County profile · official public datasets

Beaverhead County, MT

226 public highway bridges tracked in the FHWA National Bridge Inventory: 23.9% rated Good, 66.8% Fair, 9.3% Poor.

226
Public bridges: 23.9%
Good condition: 9.3%
Poor condition

The verdict

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

Beaverhead County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

42nd
of 56 on Poor share: 9.3%
Poor-condition share: 226
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.

Beaverhead County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Beaverhead County ranks #42 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.3%). Beaverhead County, Montana contains 226 public highway bridges. Roughly 23.9% are rated “Good,” 66.8% “Fair,” and 9.3% “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.

Total bridges

226

Public highway bridges in Beaverhead County

Good condition

23.9%

54 of 226 rated 7-9

Fair condition

66.8%

151 of 226 rated 5-6

Poor condition

9.3%

21 of 226 rated 4 or below

In-state Poor-share rank

#42 of 56

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

Condition distribution

Share of 226 NBI-tracked bridges by lowest applicable component rating.

Good

23.9% (54)

Fair

66.8% (151)

Poor

9.3% (21)

Beaverhead County's Poor-condition bridges carry 6,044 vehicle crossings a day

That is 3.2% of the county's reported daily bridge traffic on 9.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 288 crossings a day against 406 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 226 of 226 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

46.9% of Beaverhead County's bridges have passed the 50-year mark

106 of the 226 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 23.9% 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 44% of the county's Poor-condition bridge traffic

HWY 91 N over BEAVERHEAD RIVER 033, built 1946, carries 2,660 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 21-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 6,044 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

2
1910s

3
1920s

3
1930s

5
1940s

5
1950s

15
1960s

35
1970s

45
1980s

60
1990s

10
2000s

11
2010s

23
2020s

9

What this shows Construction peaked in the 1980s, when 60 of the county's bridges still in the inventory were built, which is 26.5% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1978) matches the Montana average (1977).

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

The 5 Montana counties nearest Beaverhead County in number of bridges, with their condition splits. Its 9.3% Poor share is the 5th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1978 is in line with the group.

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

Bridge inventory size and condition shares for Beaverhead County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Beaverhead County (this page)	226	23.9%	66.8%	9.3%	1978
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

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

Similar inventory size

Nearest county inventories outside MT (226 bridges here).

Faribault County, MN · 226 bridges
Oktibbeha County, MS · 226 bridges
Columbus County, NC · 226 bridges
Jefferson County, OH · 226 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 226 Good 54 Fair 151 Poor 21

All bridges (226)

Sort:

Beaverhead County Bridge Snapshot

Condition distribution

Beaverhead County's Poor-condition bridges carry 6,044 vehicle crossings a day

46.9% of Beaverhead County's bridges have passed the 50-year mark

One structure carries 44% of the county's Poor-condition bridge traffic

How Beaverhead 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 (226)

I 15

I 15

I 15

CO RD 002 FH 73

CO RD 002 FH 73

LOWER N FORK RD

TWIN LAKES RD

BIG LAKE CR

SAGE CREEK RD

BIG SHEEP CR RD

S 43 FH 20

S 278

I 15

I 15

I 15

CO RD 002 FH 73

I 15

I 15 FRONTAGE RD

S 89

I 15

I 15

CO RD 002 FH 73

S 43

I 15

I 15

I 15

I 15

S 89

MT HWY 91

FDR 1278

LAKNAR LN

FDR 192

I 15

I 15

I 15

I 15

I 15

I 15

MINER LAKE RD

ANDERSON LANE

NFSR #1137

I 15

I 15

I 15

I 15

RED ROCK ROAD

I 15

I 15

I 15

FRONTAGE ROAD 280

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