County profile · official public datasets

Rosebud County, MT

114 public highway bridges tracked in the FHWA National Bridge Inventory: 18.4% rated Good, 76.3% Fair, 5.3% Poor.

114
Public bridges: 18.4%
Good condition: 5.3%
Poor condition

The verdict

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

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

Top 41%
lowest Poor share in state: 5.3%
Poor-condition share: 114
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.

Rosebud County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Rosebud County ranks #23 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.3%). Rosebud County, Montana contains 114 public highway bridges. Roughly 18.4% are rated “Good,” 76.3% “Fair,” and 5.3% “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

114

Public highway bridges in Rosebud County

Good condition

18.4%

21 of 114 rated 7-9

Fair condition

76.3%

87 of 114 rated 5-6

Poor condition

5.3%

6 of 114 rated 4 or below

In-state Poor-share rank

#23 of 56

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

Condition distribution

Share of 114 NBI-tracked bridges by lowest applicable component rating.

Good

18.4% (21)

Fair

76.3% (87)

Poor

5.3% (6)

Rosebud County's Poor-condition bridges carry 1,340 vehicle crossings a day

That is 1.6% of the county's reported daily bridge traffic on 5.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 223 crossings a day against 513 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 114 of 114 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

52.6% of Rosebud County's bridges have passed the 50-year mark

60 of the 114 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 18.4% 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 44.7% of the county's Poor-condition bridge traffic

OLD HWY 10 E over SMITH CREEK 053, built 1928, carries 599 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 6-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,340 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

4
1930s

7
1940s

16
1950s

2
1960s

7
1970s

37
1980s

18
1990s

2
2000s

8
2010s

12
2020s

1

What this shows Construction peaked in the 1970s, when 37 of the county's bridges still in the inventory were built, which is 32.5% 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).

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

The 5 Montana counties nearest Rosebud County in number of bridges, with their condition splits. Its 5.3% Poor share is the 1st-lowest of these 6. Its average build year of 1973 against a peer-group mean of 1981 is 8 years older.

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

Bridge inventory size and condition shares for Rosebud County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Park County	124	21%	68.5%	10.5%	1976
Sanders County	120	40%	52.5%	7.5%	1979
Lake County	117	57.3%	27.4%	15.4%	1995
Rosebud County (this page)	114	18.4%	76.3%	5.3%	1973
Powell County	113	25.7%	68.1%	6.2%	1981
Dawson County	109	8.3%	85.3%	6.4%	1972

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

Similar inventory size

Nearest county inventories outside MT (114 bridges here).

Calhoun County, AR · 114 bridges
Schuyler County, IL · 114 bridges
Brown County, IN · 114 bridges
Morgan County, KY · 114 bridges

Similar average build year

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

Jefferson County, AL · avg 1973 · 1,068 bridges
Erie County, NY · avg 1973 · 906 bridges
Davidson County, TN · avg 1973 · 832 bridges
Lancaster County, PA · avg 1973 · 801 bridges

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

All 114 Good 21 Fair 87 Poor 6

All bridges (114)

Sort:

Rosebud County Bridge Snapshot

Condition distribution

Rosebud County's Poor-condition bridges carry 1,340 vehicle crossings a day

52.6% of Rosebud County's bridges have passed the 50-year mark

One structure carries 44.7% of the county's Poor-condition bridge traffic

How Rosebud 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 (114)

NNN RD

LEE CREEK RD

LEE CREEK RD

BRIDGE RD

SAND CREEK RD

COUNTY ROAD 105

US 12

US 12

IRR - US 212

US 12

S 446

US 12

US 12

IRR - S 39

IRR - S 39

OLD HWY 10

OLD HWY 10

US 12

US 12

US 12

S 446

SAND CREEK RD W

ROSEBUD CREEK RD

W FK AMELLS CR RD

SCHIFFER RD

IRR - S 39

IRR - S 39

ROSEBUD CREEK RD

SAND CREEK RD

IRR BIA RTE 4

IRR BIA RTE 204

I 94

OLD HWY 10

US 12

S 566-TONGUE R RD

I 94

US 12

IRR - L44235

S 447

S 447

I 94

I 94

FRONTAGE ROAD 020

OLD HWY 10 E

IRR - S 39

I 94

I 94

I 94

ROSEBUD CREEK RD

OLD HWY 10 E

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