County profile · official public datasets

Bonner County, ID

104 public highway bridges tracked in the FHWA National Bridge Inventory: 37.5% rated Good, 53.8% Fair, 8.7% Poor.

104
Public bridges: 37.5%
Good condition: 8.7%
Poor condition

The verdict

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

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

35th
of 44 on Poor share: 8.7%
Poor-condition share: 104
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.

Bonner County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Bonner County ranks #35 of 44 Idaho counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.7%). Bonner County, Idaho contains 104 public highway bridges. Roughly 37.5% are rated “Good,” 53.8% “Fair,” and 8.7% “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

104

Public highway bridges in Bonner County

Good condition

37.5%

39 of 104 rated 7-9

Fair condition

53.8%

56 of 104 rated 5-6

Poor condition

8.7%

9 of 104 rated 4 or below

In-state Poor-share rank

#35 of 44

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

Condition distribution

Share of 104 NBI-tracked bridges by lowest applicable component rating.

Good

37.5% (39)

Fair

53.8% (56)

Poor

8.7% (9)

Bonner County's Poor-condition bridges carry 7,840 vehicle crossings a day

That is 3.4% of the county's reported daily bridge traffic on 8.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 871 crossings a day against 2,584 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 104 of 104 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

45.2% of Bonner County's bridges have passed the 50-year mark

47 of the 104 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 37.5% 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 66.3% of the county's Poor-condition bridge traffic

US 2 over PRIEST RIVER, built 1962, carries 5,200 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 7,840 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

3
1940s

2
1950s

13
1960s

13
1970s

22
1980s

14
1990s

5
2000s

7
2010s

21
2020s

4

What this shows Construction peaked in the 1970s, when 22 of the county's bridges still in the inventory were built, which is 21.2% 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 Bonner County compares with Idaho's closest counties by inventory size

The 5 Idaho counties nearest Bonner County in number of bridges, with their condition splits. Its 8.7% Poor share is the 5th-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Bonner County and the 5 Idaho counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Latah County	115	35.7%	64.3%	0%	1978
Lemhi County	112	53.6%	40.2%	6.3%	1988
Jerome County	110	10%	80.9%	9.1%	1974
Bonner County (this page)	104	37.5%	53.8%	8.7%	1983
Elmore County	97	25.8%	70.1%	4.1%	1977
Blaine County	96	25%	71.9%	3.1%	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 Bonner 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 Bonner County, both outside Idaho so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside ID (104 bridges here).

Nassau County, FL · 104 bridges
Brooks County, GA · 104 bridges
Grady County, GA · 104 bridges
Martin County, IN · 104 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 104 Good 39 Fair 56 Poor 9

All bridges (104)

Sort:

Bonner County Bridge Snapshot

Condition distribution

Bonner County's Poor-condition bridges carry 7,840 vehicle crossings a day

45.2% of Bonner County's bridges have passed the 50-year mark

One structure carries 66.3% of the county's Poor-condition bridge traffic

How Bonner 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 (104)

FS ROUTE NO. 419

BOTTLE BAY RD

MID. FK. EAST R RD

SQUAW VALLEY

RAPID LIGHTNING RD

RAPID LIGHTNING RD

FS ROUTE NO. 2236

RAPID LIGHTNING RD

RAPID LIGHTNING RD

CARIBOU CK;NF-2684

US 95

WHISKEY JACK

POIRIRE RANCH RD

STC 5786;COLBURN

SH 200

FS ROUTE NO. 312

STC 7785;BRIDGE ST

RAPID LIGHTNING RD

WOODLAND DRIVE

SH 57

FS ROUTE NO. 419

FS ROUTE NO. 1082

FS ROUTE NO. 419

STC 5784;PACK RVR

US 2

W SELLE ROAD

NORTHWEST PASSAGE

STC 7715;BRONX RD

FS ROUTE NO. 311

US 95

FS ROUTE NO. 1399

NO DATA ENTERED

SH 57

STC 5783;PENINSULA

SUNNY SIDE ROAD

US 2

SH 200

US 95

FS ROUTE 1013

FS ROUTE 1013

SH 200

SH 200

STC 5783;EAST SIDE

EAST SHORE RD

FS ROUTE NO. 278

GREAT ESCAPE

JOHNSON ROAD

SH 200

STC 5770;WISCONSIN

GROUSE CREEK RD

Related