County profile · official public datasets

Adams County, ID

87 public highway bridges tracked in the FHWA National Bridge Inventory: 32.2% rated Good, 57.5% Fair, 10.3% Poor.

87
Public bridges: 32.2%
Good condition: 10.3%
Poor condition

The verdict

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

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

42nd
of 44 on Poor share: 10.3%
Poor-condition share: 87
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.

Adams County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Adams County ranks #42 of 44 Idaho counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10.3%). Adams County, Idaho contains 87 public highway bridges. Roughly 32.2% are rated “Good,” 57.5% “Fair,” and 10.3% “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

Public highway bridges in Adams County

Good condition

32.2%

28 of 87 rated 7-9

Fair condition

57.5%

50 of 87 rated 5-6

Poor condition

10.3%

9 of 87 rated 4 or below

In-state Poor-share rank

#42 of 44

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

Condition distribution

Share of 87 NBI-tracked bridges by lowest applicable component rating.

Good

32.2% (28)

Fair

57.5% (50)

Poor

10.3% (9)

Adams County's Poor-condition bridges carry 443 vehicle crossings a day

That is 1.1% of the county's reported daily bridge traffic on 10.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 49 crossings a day against 665 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 87 of 87 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

52.9% of Adams County's bridges have passed the 50-year mark

46 of the 87 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 32.2% 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 22.6% of the county's Poor-condition bridge traffic

OLD HORNET ROAD over HORNET CREEK, built 1949, 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 443 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1920s

4
1930s

5
1940s

1
1950s

11
1960s

16
1970s

15
1980s

9
1990s

3
2000s

9
2010s

8
2020s

5

What this shows Construction peaked in the 1960s, when 16 of the county's bridges still in the inventory were built, which is 18.4% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1975) matches the Idaho average (1979).

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

The 5 Idaho counties nearest Adams County in number of bridges, with their condition splits. Its 10.3% Poor share is the 6th-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1976 is in line with the group.

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

Bridge inventory size and condition shares for Adams County and the 5 Idaho counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Boise County	88	46.6%	47.7%	5.7%	1978
Clearwater County	88	43.2%	51.1%	5.7%	1973
Adams County (this page)	87	32.2%	57.5%	10.3%	1975
Boundary County	83	32.5%	57.8%	9.6%	1982
Gooding County	80	16.3%	76.3%	7.5%	1965
Madison County	80	30%	70%	0%	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 Adams 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 Adams County, both outside Idaho so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside ID (87 bridges here).

Modoc County, CA · 87 bridges
Hendry County, FL · 87 bridges
Humboldt County, IA · 87 bridges
Rockcastle County, KY · 87 bridges

Similar average build year

Nearest mean year-built outside ID (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 87 Good 28 Fair 50 Poor 9

All bridges (87)

Sort:

Adams County Bridge Snapshot

Condition distribution

Adams County's Poor-condition bridges carry 443 vehicle crossings a day

52.9% of Adams County's bridges have passed the 50-year mark

One structure carries 22.6% of the county's Poor-condition bridge traffic

How Adams 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 (87)

ROAD TO CAMPGROUND

SHAW LANE

JACKSON CREEK ROAD

NO DATA ENTERED

MUNDY GULCH ROAD

NO DATA ENTERED

NFSR 50172

COTTONWOOD ROAD

HUBBARD ROAD

RIDGE ROAD

US 95

FALL CREEK ROAD

WILDHORSE RD

LITTLE WEISER

NF ROAD 105

NO DATA ENTERED

US 95

US 95

STC3892;INDIAN VLY

FARRELL ROAD

US 95

NF ROAD 105

NF ROAD 105

US 95

MIDDLE FORK ROAD

FRUITVALE ROAD

US 95

UPPER DALE ROAD

MIDDLE FORK ROAD

WILDHORSE ROAD

JACKSON CREEK RD

AIRPORT RD

OLD HORNET ROAD

OLD HWY 95

CEMETARY RD

NO DATA ENTERED

OR 86 (HWY 012)

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