County profile · official public datasets

Fergus County, MT

158 public highway bridges tracked in the FHWA National Bridge Inventory: 31.6% rated Good, 62% Fair, 6.3% Poor.

158
Public bridges: 31.6%
Good condition: 6.3%
Poor condition

The verdict

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

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

31st
of 56 on Poor share: 6.3%
Poor-condition share: 158
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.

Fergus County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Fergus County ranks #31 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). Fergus County, Montana contains 158 public highway bridges. Roughly 31.6% are rated “Good,” 62% “Fair,” and 6.3% “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

158

Public highway bridges in Fergus County

Good condition

31.6%

50 of 158 rated 7-9

Fair condition

62%

98 of 158 rated 5-6

Poor condition

6.3%

10 of 158 rated 4 or below

In-state Poor-share rank

#31 of 56

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

Condition distribution

Share of 158 NBI-tracked bridges by lowest applicable component rating.

Good

31.6% (50)

Fair

62% (98)

Poor

6.3% (10)

Fergus County's Poor-condition bridges carry 3,802 vehicle crossings a day

That is 4% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 380 crossings a day against 449 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 158 of 158 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

44.9% of Fergus County's bridges have passed the 50-year mark

71 of the 158 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 31.6% 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 37.9% of the county's Poor-condition bridge traffic

US 87 over DRAINAGE, built 1939, carries 1,442 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 3,802 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1920s

4
1930s

16
1940s

9
1950s

10
1960s

27
1970s

15
1980s

25
1990s

7
2000s

9
2010s

18
2020s

17

What this shows Construction peaked in the 1960s, when 27 of the county's bridges still in the inventory were built, which is 17.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1978) matches the Montana average (1977).

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

The 5 Montana counties nearest Fergus County in number of bridges, with their condition splits. Its 6.3% Poor share is the 5th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1974 is in line with the group.

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

Bridge inventory size and condition shares for Fergus County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Cascade County	185	41.6%	54.6%	3.8%	1965
Fergus County (this page)	158	31.6%	62%	6.3%	1978
Mineral County	152	25.7%	64.5%	9.9%	1971
Ravalli County	148	41.2%	53.4%	5.4%	1981
Big Horn County	135	26.7%	68.1%	5.2%	1978
Jefferson County	134	17.9%	76.9%	5.2%	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 Fergus 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 Fergus County, both outside Montana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MT (158 bridges here).

Napa County, CA · 158 bridges
Wells County, IN · 158 bridges
Jackson County, MI · 158 bridges
Yalobusha County, MS · 158 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 158 Good 50 Fair 98 Poor 10

All bridges (158)

Sort:

Fergus County Bridge Snapshot

Condition distribution

Fergus County's Poor-condition bridges carry 3,802 vehicle crossings a day

44.9% of Fergus County's bridges have passed the 50-year mark

One structure carries 37.9% of the county's Poor-condition bridge traffic

How Fergus 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 (158)

COUNTY ROAD

MATOVICH RD

ANDREWS ROAD

GLENGARY RD

COUNTY ROAD 144

JUDITH RIVER RD

US 87

ROUNDHOUSE RD

US 191

S 81

STAFFORD FERRY RD

S 547

COTTONWOOD CR RD

COTTONWOOD CUTOFF

FOREST GROVE RD

JOYLAND RD

FISH HATCHERY RD

FORT MAGINNIS RD

SCOTT CROSSING

US 87

FARREN HILL ROAD

TOGNETTI RD

CARROLL TRAIL

SANDROCK RD

TIMBERLINE RD

HORSE RANCH RD

US 191

COTTONWOOD CR RD

CHRISTINA ST W

BAIN STREET

MABEE RD

S 200

FOREST GROVE RD

S 19

STONE BARN LN

P 81

P-81

S 19

S-81

S 19

HORSE RANCH RD

S 19

S 19

US 87

S 19

STAFFORD FERRY RD

US 87

US 191

6TH AVE S

W BROADWAY STREET

Related