County profile · official public datasets

Teton County, MT

82 public highway bridges tracked in the FHWA National Bridge Inventory: 42.7% rated Good, 54.9% Fair, 2.4% Poor.

82
Public bridges: 42.7%
Good condition: 2.4%
Poor condition

The verdict

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

Teton County posts a top-quartile lowest Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 14%
lowest Poor share in state: 2.4%
Poor-condition share: 82
public highway bridges: 1975
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.

Teton County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Teton County ranks #8 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.4%). Teton County, Montana contains 82 public highway bridges. Roughly 42.7% are rated “Good,” 54.9% “Fair,” and 2.4% “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 Teton County

Good condition

42.7%

35 of 82 rated 7-9

Fair condition

54.9%

45 of 82 rated 5-6

Poor condition

2.4%

2 of 82 rated 4 or below

In-state Poor-share rank

#8 of 56

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

Condition distribution

Share of 82 NBI-tracked bridges by lowest applicable component rating.

Good

42.7% (35)

Fair

54.9% (45)

Poor

2.4% (2)

Teton County's Poor-condition bridges carry 200 vehicle crossings a day

That is 0.7% of the county's reported daily bridge traffic on 2.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 100 crossings a day against 387 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 82 of 82 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

42.7% of Teton County's bridges have passed the 50-year mark

35 of the 82 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 42.7% 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 50% of the county's Poor-condition bridge traffic

8TH LN NE over GREENFIELD SO CANAL 039, built 1966, 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 200 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

8
1940s

3
1950s

4
1960s

12
1970s

25
1980s

17
1990s

3
2000s

3
2010s

7

What this shows Construction peaked in the 1970s, when 25 of the county's bridges still in the inventory were built, which is 30.5% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1975) matches the Montana average (1977).

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

The 5 Montana counties nearest Teton County in number of bridges, with their condition splits. Its 2.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1977 is in line with the group.

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

Bridge inventory size and condition shares for Teton County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Stillwater County	92	30.4%	68.5%	1.1%	1977
Teton County (this page)	82	42.7%	54.9%	2.4%	1975
Carbon County	80	36.3%	58.8%	5%	1985
Granite County	73	37%	52.1%	11%	1974
Custer County	71	14.1%	84.5%	1.4%	1969
Glacier County	71	38%	56.3%	5.6%	1978

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

Similar inventory size

Nearest county inventories outside MT (82 bridges here).

Murray County, GA · 82 bridges
Gallatin County, IL · 82 bridges
Thomas County, KS · 82 bridges
Nicholas County, KY · 82 bridges

Similar average build year

Nearest mean year-built outside MT (1975 here).

San Bernardino County, CA · avg 1975 · 1,422 bridges
Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges

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

All 82 Good 35 Fair 45 Poor 2

Fair-condition bridges (45)

Sort:

Teton County Bridge Snapshot

Condition distribution

Teton County's Poor-condition bridges carry 200 vehicle crossings a day

42.7% of Teton County's bridges have passed the 50-year mark

One structure carries 50% of the county's Poor-condition bridge traffic

How Teton 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

Fair-condition bridges (45)

2ND LN SE

NFSR 8982

SHERMAN RD

NFSR #144

BELLVIEW RD

7TH LN NE

1ST LN SE

COUNTY LINE RD

AIRPORT RD

I 15

I 15

SO. FK. TETON RD.

US 89

US 287

9TH LN NW

4TH LN NE

S 565

1ST RD SW

I 15

US 287

S 221

BLACKLEAF RD

3RD LN NW

13TH LN NE

FOSTER RD

S 431

5TH LN NE

US 287

ROUTE 108

5TH LN NE

PEEBLES RD

S 408

BELLVIEW RD

PISHKUN RD

20TH RD NW

S DIVISION LN

PENDROY RD

15TH LN NW

9TH RD NE

S 431

S 431

S 408

6TH LN NE

20TH LN NE

8TH LN NE

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