County profile · official public datasets

Fremont County, ID

137 public highway bridges tracked in the FHWA National Bridge Inventory: 32.8% rated Good, 61.3% Fair, 5.8% Poor.

137
Public bridges: 32.8%
Good condition: 5.8%
Poor condition

The verdict

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

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

27th
of 44 on Poor share: 5.8%
Poor-condition share: 137
public highway bridges: 1983
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.

Fremont County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Fremont County ranks #27 of 44 Idaho counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.8%). Fremont County, Idaho contains 137 public highway bridges. Roughly 32.8% are rated “Good,” 61.3% “Fair,” and 5.8% “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

137

Public highway bridges in Fremont County

Good condition

32.8%

45 of 137 rated 7-9

Fair condition

61.3%

84 of 137 rated 5-6

Poor condition

5.8%

8 of 137 rated 4 or below

In-state Poor-share rank

#27 of 44

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

Condition distribution

Share of 137 NBI-tracked bridges by lowest applicable component rating.

Good

32.8% (45)

Fair

61.3% (84)

Poor

5.8% (8)

Fremont County's Poor-condition bridges carry 1,390 vehicle crossings a day

That is 0.7% of the county's reported daily bridge traffic on 5.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 174 crossings a day against 1,322 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 137 of 137 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

28.5% of Fremont County's bridges have passed the 50-year mark

39 of the 137 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 32.8% 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 86.3% of the county's Poor-condition bridge traffic

STC 6774;TETON HWY over S.FK.TETON RIVER, built 1977, carries 1,200 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 8-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,390 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

1
1930s

6
1940s

1
1950s

6
1960s

16
1970s

34
1980s

23
1990s

17
2000s

7
2010s

21
2020s

5

What this shows Construction peaked in the 1970s, when 34 of the county's bridges still in the inventory were built, which is 24.8% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1983) matches the Idaho average (1979).

How Fremont County compares with Idaho's closest counties by inventory size

The 5 Idaho counties nearest Fremont County in number of bridges, with their condition splits. Its 5.8% Poor share is the 4th-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1977 is 6 years newer.

Showing the 5 closest of 43 Idaho counties eligible for comparison.

Bridge inventory size and condition shares for Fremont County and the 5 Idaho counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Valley County	149	45%	48.3%	6.7%	1982
Fremont County (this page)	137	32.8%	61.3%	5.8%	1983
Custer County	128	34.4%	56.3%	9.4%	1978
Jefferson County	127	17.3%	79.5%	3.1%	1973
Twin Falls County	126	12.7%	84.1%	3.2%	1973
Bannock County	124	33.1%	62.1%	4.8%	1981

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

Similar inventory size

Nearest county inventories outside ID (137 bridges here).

Fremont County, CO · 137 bridges
Prowers County, CO · 137 bridges
Orange County, IN · 137 bridges
Shelby County, KY · 137 bridges

Similar average build year

Nearest mean year-built outside ID (1983 here).

Dallas County, TX · avg 1983 · 3,230 bridges
Bexar County, TX · avg 1983 · 2,342 bridges
Sedgwick County, KS · avg 1983 · 1,333 bridges
Will County, IL · avg 1983 · 649 bridges

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

All 137 Good 45 Fair 84 Poor 8

All bridges (137)

Sort:

Fremont County Bridge Snapshot

Condition distribution

Fremont County's Poor-condition bridges carry 1,390 vehicle crossings a day

28.5% of Fremont County's bridges have passed the 50-year mark

One structure carries 86.3% of the county's Poor-condition bridge traffic

How Fremont County compares with Idaho'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 (137)

N 700 WEST STREET

ASHTON-FLAGG RANCH

CONANT CREEK WAY

E 600 N

US 20 EBL & WBL

SH 32

SH 33

SH 47

N 2750 E

US 20

SH 33

US 20 WBL

US 20B

N 2100 E

N 2600 E

US 20

N 2900 E; ORA ST

SH 87

S6805;YALE-KILGORE

N 3800 E

US 20

US 20

SH 87

US 20 EBL

US 20 EBL & WBL

US 20 EBL & WBL

STC 6770;SALEM RD

US 20B

US 20

STC 6774;N 2400 E

E 800 N

US 20B

US 20B

E 200 N

ROAD

N 1700 E

US 20B;BRIDGE ST

STC 6774;N 2400 E

N 4525 E

20097

N 1700 E

ROAD

E 800 N

STC 6774;TETON HWY

E 500 N

STC 6760;E 400 N

N 2300 E

HIGH TOP LANE

ROAD

N 2500 E

Related