County profile · official public datasets

Carter County, MT

41 public highway bridges tracked in the FHWA National Bridge Inventory: 31.7% rated Good, 63.4% Fair, 4.9% Poor.

41
Public bridges: 31.7%
Good condition: 4.9%
Poor condition

The verdict

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

Carter County pairs a better-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 32%
lowest Poor share in state: 4.9%
Poor-condition share: 41
public highway bridges: 1985
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.

Carter County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Carter County ranks #18 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.9%). Carter County, Montana contains 41 public highway bridges. Roughly 31.7% are rated “Good,” 63.4% “Fair,” and 4.9% “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

Public highway bridges in Carter County

Good condition

31.7%

13 of 41 rated 7-9

Fair condition

63.4%

26 of 41 rated 5-6

Poor condition

4.9%

2 of 41 rated 4 or below

In-state Poor-share rank

#18 of 56

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

Condition distribution

Share of 41 NBI-tracked bridges by lowest applicable component rating.

Good

31.7% (13)

Fair

63.4% (26)

Poor

4.9% (2)

Carter County's Poor-condition bridges carry 860 vehicle crossings a day

That is 6.3% of the county's reported daily bridge traffic on 4.9% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 430 crossings a day against 116 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 41 of 41 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

36.6% of Carter County's bridges have passed the 50-year mark

15 of the 41 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 31.7% 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 54.7% of the county's Poor-condition bridge traffic

S 7 over DRAINAGE, built 1940, carries 470 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 860 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

4
1940s

6
1950s

2
1960s

3
1980s

5
1990s

1
2000s

3
2010s

17

What this shows Construction peaked in the 2010s, when 17 of the county's bridges still in the inventory were built, which is 41.5% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1985, 8 years newer than the Montana average of 1977.

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

The 5 Montana counties nearest Carter County in number of bridges, with their condition splits. Its 4.9% Poor share is the 2nd-lowest of these 6. Its average build year of 1985 against a peer-group mean of 1984 is in line with the group.

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

Bridge inventory size and condition shares for Carter County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Hill County	46	58.7%	34.8%	6.5%	1983
McCone County	44	11.4%	79.5%	9.1%	1967
Chouteau County	42	54.8%	38.1%	7.1%	1981
Carter County (this page)	41	31.7%	63.4%	4.9%	1985
Broadwater County	37	27%	67.6%	5.4%	1990
Fallon County	37	45.9%	51.4%	2.7%	1998

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

Similar inventory size

Nearest county inventories outside MT (41 bridges here).

Saguache County, CO · 41 bridges
Echols County, GA · 41 bridges
Pike County, GA · 41 bridges
Ohio County, IN · 41 bridges

Similar average build year

Nearest mean year-built outside MT (1985 here).

Hillsborough County, FL · avg 1985 · 840 bridges
Lancaster County, NE · avg 1985 · 661 bridges
Nueces County, TX · avg 1985 · 528 bridges
Grayson County, TX · avg 1985 · 513 bridges

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

All 41 Good 13 Fair 26 Poor 2

All bridges (41)

Sort:

Carter County Bridge Snapshot

Condition distribution

Carter County's Poor-condition bridges carry 860 vehicle crossings a day

36.6% of Carter County's bridges have passed the 50-year mark

One structure carries 54.7% of the county's Poor-condition bridge traffic

How Carter 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 (41)

MILES CITY CUTOFF

COTTONWOOD CR RD

COTTONWOOD CR RD

S 323

MOORE RD

CENTRAL AVE

S 7

S 7

PADDEN RD

LITTLE MISSOURI RD

STAGVILLE DRAW RD

LITTLE MISSOURI RD

US 212

S 323

MILL IRON CAMP CRO

S 7

US 212

S 7

MORMON AVE

HAMMOND RD

POWDERVILLE RD

PLEVNA ROAD

HAMMOND RD

HAMMOND RD

US 212

RIDGE RD

CROW CREEK ROAD

LITTLE MISSOURI RD

LITTLE MISSOURI RD

TAUCK RD

COTTONWOOD CR RD

LITTLE MISSOURI RD

ISMAY RD

TAUCK RD

Chicago AVE

CAPITOL RD

COTTONWOOD CR RD

CROW CREEK RD

LARSON LOOP RD

S 7

S 7

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