County profile · official public datasets

Deer Lodge County, MT

68 public highway bridges tracked in the FHWA National Bridge Inventory: 27.9% rated Good, 66.2% Fair, 5.9% Poor.

68
Public bridges
27.9%
Good condition
5.9%
Poor condition

The verdict

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

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

29th
of 56 on Poor share
5.9%
Poor-condition share
68
public highway bridges
1973
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.

Deer Lodge County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Deer Lodge County ranks #29 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.9%). Deer Lodge County, Montana contains 68 public highway bridges. Roughly 27.9% are rated “Good,” 66.2% “Fair,” and 5.9% “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

68

Public highway bridges in Deer Lodge County

Good condition

27.9%

19 of 68 rated 7-9

Fair condition

66.2%

45 of 68 rated 5-6

Poor condition

5.9%

4 of 68 rated 4 or below

In-state Poor-share rank

#29 of 56

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

Condition distribution

Share of 68 NBI-tracked bridges by lowest applicable component rating.

Good
27.9% (19)
Fair
66.2% (45)
Poor
5.9% (4)

Deer Lodge County's Poor-condition bridges carry 270 vehicle crossings a day

That is 0.3% of the county's reported daily bridge traffic on 5.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 68 crossings a day against 1,283 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 68 of 68 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

48.5% of Deer Lodge County's bridges have passed the 50-year mark

33 of the 68 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 27.9% 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 37% of the county's Poor-condition bridge traffic

COUNTY ROAD 098 over CLARK FORK RIVER 020, built 1920, 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 4-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 270 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Deer Lodge County's bridges were built

68 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1970s, when 18 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 45 to 54 years old in the 2024 inventory. Its average build year (1973) matches the Montana average (1977).

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

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

The 5 Montana counties nearest Deer Lodge County in number of bridges, with their condition splits. Its 5.9% Poor share is the 5th-lowest of these 6. Its average build year of 1973 against a peer-group mean of 1975 is in line with the group.

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

Bridge inventory size and condition shares for Deer Lodge County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Granite County 73 11%
Custer County 71 1.4%
Glacier County 71 5.6%
Silver Bow County 68 1.5%
Deer Lodge County (this page) 68 5.9%
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 Deer Lodge 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 Deer Lodge County, both outside Montana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MT (68 bridges here).

Similar average build year

Nearest mean year-built outside MT (1973 here).

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

All 68 Good 19 Fair 45 Poor 4

Good-condition bridges (19)

NO DATA ENTERED

Good

Over: WARM SPRINGS CR

ROAD TO REC RESIDENCE, Deer Lodge, MT

Built 2016 ADT: 50

FRONTAGE ROAD 146

Good

Over: DRAINAGE 032

3M S WARM SPRINGS, Deer Lodge, MT

Built 1931 Load: 23.6 t ADT: 100

S 43

Good

Over: LAMARCHE CREEK

14M NW WISE RIVER, Deer Lodge, MT

Built 1941 Load: 24.5 t ADT: 454

I 90

Good

Over: INT WARM SPRINGS

WARM SPRINGS, Deer Lodge, MT

Built 1978 Load: 26.3 t ADT: 5,740

I 90

Good

Over: INT WARM SPRINGS

WARM SPRINGS, Deer Lodge, MT

Built 1978 Load: 26.3 t ADT: 5,053

I 90

Good

Over: CLARK FORK RIVER

2.5M N OPPORTUNITY, Deer Lodge, MT

Built 1978 Load: 26.3 t ADT: 5,053

I 90

Good

Over: INT GALEN

3.7M N WARM SPRINGS, Deer Lodge, MT

Built 1978 Load: 27.2 t ADT: 5,740

S 43

Good

Over: FISHTRAP CREEK

16M NW WISE RIVER, Deer Lodge, MT

Built 1941 Load: 29.0 t ADT: 454

STUMPTOWN RD

Good

Over: WARM SPRINGS CREEK 006

4M NW ANACONDA, Deer Lodge, MT

Built 2015 Load: 32.7 t ADT: 85

FDR2488

Good

Over: NO DATA ENTERED

NO DATA ENTERED, Deer Lodge, MT

Built 1994 Load: 35.3 t ADT: 20

FDR 2469

Good

Over: NO DATA ENTERED

SEYMOUR CR., Deer Lodge, MT

Built 1994 Load: 36.0 t ADT: 20

GAS CITY RD

Good

Over: CLARK FORK RIVER 019

1M E WARM SPRINGS, Deer Lodge, MT

Built 2011 Load: 36.3 t ADT: 100

CRACKERVILLE RD

Good

Over: SILVERBOW CREEK 002

4M S OPPORTUNITY, Deer Lodge, MT

Built 2014 Load: 36.3 t ADT: 515

WILLOW GLEN RD

Good

Over: MILL CREEK 004

1M W OPPORTUNITY, Deer Lodge, MT

Built 2015 Load: 37.2 t ADT: 252

COUNTY RD 306

Good

Over: TWIN LAKES CREEK 094

8M W ANACONDA, Deer Lodge, MT

Built 2013 Load: 38.1 t ADT: 100

S 569

Good

Over: FRENCH GULCH 042

19M SW ANACONDA, Deer Lodge, MT

Built 2015 Load: 39.0 t ADT: 288

S 596

Good

Over: BIG CALIFORNIA CREEK

15M S ANACONDA, Deer Lodge, MT

Built 2019 Load: 39.9 t ADT: 288

NO DATA ENTERED

Good

Over: WARM SPRINGS CR

HIGHWAY ENTERANCE TO AJC, Deer Lodge, MT

Built 1979 Load: 46.7 t ADT: 50

NO DATA ENTERED

Good

Over: STORM LAKE CREEK

NO DATA ENTERED, Deer Lodge, MT

Built 2011 Load: 65.4 t ADT: 10

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.