County profile · official public datasets

Sanders County, MT

120 public highway bridges tracked in the FHWA National Bridge Inventory: 40% rated Good, 52.5% Fair, 7.5% Poor.

120
Public bridges
40%
Good condition
7.5%
Poor condition

The verdict

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

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

37th
of 56 on Poor share
7.5%
Poor-condition share
120
public highway bridges
1979
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.

Sanders County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Sanders County ranks #37 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.5%). Sanders County, Montana contains 120 public highway bridges. Roughly 40% are rated “Good,” 52.5% “Fair,” and 7.5% “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

120

Public highway bridges in Sanders County

Good condition

40%

48 of 120 rated 7-9

Fair condition

52.5%

63 of 120 rated 5-6

Poor condition

7.5%

9 of 120 rated 4 or below

In-state Poor-share rank

#37 of 56

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

Condition distribution

Share of 120 NBI-tracked bridges by lowest applicable component rating.

Good
40% (48)
Fair
52.5% (63)
Poor
7.5% (9)

Sanders County's Poor-condition bridges carry 4,651 vehicle crossings a day

That is 10.2% of the county's reported daily bridge traffic on 7.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 517 crossings a day against 348 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 120 of 120 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

45.8% of Sanders County's bridges have passed the 50-year mark

55 of the 120 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 40% 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 52.4% of the county's Poor-condition bridge traffic

S 200 over CLARK FORK RIVER, built 1960, carries 2,436 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 4,651 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Sanders County's bridges were built

120 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 25 of the county's bridges still in the inventory were built, which is 20.8% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1979) matches the Montana average (1977).

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

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

The 5 Montana counties nearest Sanders County in number of bridges, with their condition splits. Its 7.5% Poor share is the 4th-lowest of these 6. Its average build year of 1979 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Sanders County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Park County 124 10.5%
Sanders County (this page) 120 7.5%
Lake County 117 15.4%
Rosebud County 114 5.3%
Powell County 113 6.2%
Dawson County 109 6.4%

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

Similar inventory size

Nearest county inventories outside MT (120 bridges here).

Similar average build year

Nearest mean year-built outside MT (1979 here).

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

All 120 Good 48 Fair 63 Poor 9

All bridges (120)

S 471 FH 7

Fair

Over: COOPER CREEK

16M W THOMPSON FALLS, Sanders, MT

Built 1979 Load: 32.7 t ADT: 82

S 471 FH 7

Fair

Over: PROSPECT CREEK

18M W THOMPSON FALLS, Sanders, MT

Built 1979 Load: 32.7 t ADT: 82

NO DATA ENTERED

Fair

Over: EAST FK BULL RIVER

LOST GIRL NO 2, Sanders, MT

Built 1963 Load: 33.4 t ADT: 20

RD 7569

Fair

Over: FISHTRAP CR

RADIO MANTRAP, Sanders, MT

Built 1963 Load: 33.4 t ADT: 50

5TH AVE S

Fair

Over: CLARK FORK 085

1M SW PLAINS, Sanders, MT

Built 1975 Load: 33.6 t ADT: 100

NO DATA ENTERED

Fair

Over: EAST FK BULL RIVER

NO DATA ENTERED, Sanders, MT

Built 1963 Load: 35.0 t ADT: 30

FAR WEST RD

Fair

Over: LITTLE BITTERROOT 060

13M N CAMAS, Sanders, MT

Built 1991 Load: 37.1 t ADT: 100

IRR - S 200

Fair

Over: SEEPAY CREEK

2M SW PERMA, Sanders, MT

Built 1969 Load: 37.2 t ADT: 2,127

S 135

Fair

Over: CLARK FORK RIVER

11M SW PARADISE, Sanders, MT

Built 1962 Load: 38.1 t ADT: 1,985

IRR BIA ROUTE 166

Fair

Over: REVAIS CREEK

4.0K SOUTH OF HWY 200, Sanders, MT

Built 2014 Load: 46.3 t ADT: 30

NO DATA ENTERED

Fair

Over: N BRANCH MARTEN CREEK

MARTEN CREEK, Sanders, MT

Built 1967 Load: 49.9 t ADT: 20

ELK CREEK RD

Fair

Over: ELK CREEK 051

4M S HERON, Sanders, MT

Built 1988 Load: 56.2 t ADT: 100

IRR BIA RTE 127

Fair

Over: MILL POCKET-CAMAS CANAL

6.3KM NW OF NIARADA, Sanders, MT

Built 2004 Load: 65.3 t ADT: 10

ACM RD

Good

Over: THOMPSON RIVER

ACM RD, Sanders, MT

Built 1996 ADT: 50

NO DATA ENTERED

Good

Over: BIG BEAVER

NO DATA ENTERED, Sanders, MT

Built 1976 Load: 15.6 t ADT: 20

RD 7611

Good

Over: CLEAR CR

DIRTY-CLEAR RD, Sanders, MT

Built 1991 Load: 18.1 t ADT: 50

NO DATA ENTERED

Good

Over: PROSPECT CREEK

COX GULCH, Sanders, MT

Built 1974 Load: 18.1 t ADT: 50

HERON RD

Good

Over: CABINET GORGE RES 049

1M W HERON, Sanders, MT

Built 2017 Load: 19.1 t ADT: 529

IRR - S 200

Good

Over: REVAIS CREEK

3M W DIXON, Sanders, MT

Built 1989 Load: 22.7 t ADT: 1,943

RACE HORSE GULCH R

Good

Over: CAMAS CREEK 016

E PERMA, Sanders, MT

Built 1992 Load: 23.8 t ADT: 100

NO DATA ENTERED

Good

Over: NO DATA ENTERED

NO DATA ENTERED, Sanders, MT

Built 2005 Load: 24.9 t ADT: 40

NO DATA ENTERED

Good

Over: WEST FORK DRY CREEK

W FK DRY CR, Sanders, MT

Built 1992 Load: 25.9 t ADT: 40

UPPER RESERVOIR RD

Good

Over: IRRIGATION CANAL 069

4M N LONEPINE, Sanders, MT

Built 1991 Load: 27.2 t ADT: 100

NO DATA ENTERED

Good

Over: COOPER CREEK

NO DATA ENTERED, Sanders, MT

Built 2000 Load: 27.9 t ADT: 40

NO DATA ENTERED

Good

Over: ROCK CR

NO DATA ENTERED, Sanders, MT

Built 1959 Load: 28.2 t ADT: 50

S 556-THOMPSON R R

Good

Over: BIG ROCK CREEK

35M SW MARION, Sanders, MT

Built 2009 Load: 28.8 t ADT: 55

IRR - S 200

Good

Over: MAGPIE CREEK

5M SE PERMA, Sanders, MT

Built 1986 Load: 29.0 t ADT: 1,943

EKBLAD ROAD

Good

Over: HOT SPRINGS CREEK 101

NE HOT SPRINGS, Sanders, MT

Built 2010 Load: 29.8 t ADT: 100

GREEN MOUNTAIN RD

Good

Over: SWAMP CREEK 030

5M N TROUT CREEK, Sanders, MT

Built 1986 Load: 29.9 t ADT: 100

BIG GULCH RD

Good

Over: LITTLE BITTERROOT RIV018

9 M SE HOT SPRINGS, Sanders, MT

Built 2014 Load: 29.9 t ADT: 100

REVAIS CREEK ROAD

Good

Over: REVAIS CREEK 102

2.7M S MT 200, Sanders, MT

Built 2012 Load: 30.1 t ADT: 100

NO DATA ENTERED

Good

Over: NO DATA ENTERED

NO DATA ENTERED, Sanders, MT

Built 2010 Load: 30.5 t ADT: 50

NO DATA ENTERED

Good

Over: FISHTRAP CREEK

NO DATA ENTERED, Sanders, MT

Built 2009 Load: 30.8 t ADT: 40

VERMILION RIV RD

Good

Over: LYONS CREEK 032

7M E TROUT CREEK, Sanders, MT

Built 1900 Load: 30.8 t ADT: 100

IRR - S 212

Good

Over: JOCKO RIVER

1M E DIXON, Sanders, MT

Built 1949 Load: 30.8 t ADT: 917

RD 7618

Good

Over: WILKES CREEK

WILKES CREEK, Sanders, MT

Built 1973 Load: 31.1 t ADT: 50

STONY CREEK

Good

Over: STONY LAKE CREEK

STONY CREEK, Sanders, MT

Built 2015 Load: 31.8 t ADT: 50

STEVENS RIDGE TR

Good

Over: STEVENS CREEK 105

4 M SSE NOXON, Sanders, MT

Built 1992 Load: 32.7 t ADT: 100

ELK CREEK RD

Good

Over: ELK CREEK 050

4M S HERON, Sanders, MT

Built 2001 Load: 32.7 t ADT: 100

LOWER RIVER RD

Good

Over: ELK CREEK 100

1M E HERON, Sanders, MT

Built 1976 Load: 32.7 t ADT: 65

KLAKKEN RD

Good

Over: PILGRIM CREEK 053

E NOXON, Sanders, MT

Built 1972 Load: 32.7 t ADT: 170

WINCHESTER RD

Good

Over: ELK CREEK 057

2M S HERON, Sanders, MT

Built 1992 Load: 32.7 t ADT: 100

WILKES CREEK ROAD

Good

Over: PROSPECT CREEK 006

3M SW THOMPSON FALLS, Sanders, MT

Built 1978 Load: 32.7 t ADT: 100

THOMPSON R PASS RD

Good

Over: THOMPSON RIVER 062

23M N PLAINS, Sanders, MT

Built 1976 Load: 32.7 t ADT: 40

S 556-THOMPSON R R

Good

Over: THOMPSON RIVER

30M SW MARION, Sanders, MT

Built 1988 Load: 32.7 t ADT: 55

LIL BITTERROOT RD

Good

Over: WARM SPRING CREEK 093

4M E HOT SPRINGS, Sanders, MT

Built 2009 Load: 33.4 t ADT: 100

S 200

Good

Over: BEAVER CREEK

3M SE TROUT CREEK, Sanders, MT

Built 1986 Load: 34.5 t ADT: 2,030

S 200

Good

Over: RR

2M SE THOMPSON FALLS, Sanders, MT

Built 2000 Load: 35.4 t ADT: 2,247

W FK THOMPSON RD

Good

Over: HONEYMOON CR

THOMPSON-FISHTRAP, Sanders, MT

Built 2007 Load: 36.0 t ADT: 40

REVAIS CREEK ROAD

Good

Over: REVAIS CREEK 103

1.5M S MT 200, Sanders, MT

Built 2012 Load: 37.9 t ADT: 100

Read our methodology - how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →
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.