County profile · official public datasets

Madison County, ID

80 public highway bridges tracked in the FHWA National Bridge Inventory: 30% rated Good, 70% Fair, 0% Poor.

80
Public bridges: 30%
Good condition: 0%
Poor condition

The verdict

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

Madison County posts a top-10% lowest Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 9%
lowest Poor share in state: 0%
Poor-condition share: 80
public highway bridges: 1981
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.

Madison County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Madison County ranks #4 of 44 Idaho counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 0%). Madison County, Idaho contains 80 public highway bridges. Roughly 30% are rated “Good,” 70% “Fair,” and 0% “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 Madison County

Good condition

30%

24 of 80 rated 7-9

Fair condition

70%

56 of 80 rated 5-6

Poor condition

0 of 80 rated 4 or below

In-state Poor-share rank

#4 of 44

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

Condition distribution

Share of 80 NBI-tracked bridges by lowest applicable component rating.

Good

30% (24)

Fair

70% (56)

Poor

0% (0)

25% of Madison County's bridges have passed the 50-year mark

20 of the 80 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 30% 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.

1930s

3
1950s

3
1960s

8
1970s

33
1980s

14
1990s

4
2000s

8
2010s

5
2020s

2

What this shows Construction peaked in the 1970s, when 33 of the county's bridges still in the inventory were built, which is 41.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1981) matches the Idaho average (1979).

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

The 5 Idaho counties nearest Madison County in number of bridges, with their condition splits. Its 0% Poor share is the 1st-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1976 is 5 years newer.

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

Bridge inventory size and condition shares for Madison 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
Adams County	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
Washington County	80	32.5%	61.3%	6.3%	1979
Madison County (this page)	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 Madison 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 Madison County, both outside Idaho so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside ID (80 bridges here).

Moffat County, CO · 80 bridges
Burke County, GA · 80 bridges
Todd County, KY · 80 bridges
Iberville County, LA · 80 bridges

Similar average build year

Nearest mean year-built outside ID (1981 here).

Franklin County, OH · avg 1981 · 922 bridges
Greenville County, SC · avg 1981 · 635 bridges
Montgomery County, OH · avg 1981 · 632 bridges
McLean County, IL · avg 1981 · 624 bridges

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

All 80 Good 24 Fair 56 Poor 0

Good-condition bridges (24)

Sort:

Madison County Bridge Snapshot

Condition distribution

25% of Madison County's bridges have passed the 50-year mark

How Madison 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

Good-condition bridges (24)

S. SNAKE RIVER RD

US 20 EBL

US 20 WBL

US 20 EBL

US 20 WBL

US 20 EBL

N 3000 E

N 3000 E

S6780;SALEM CHURCH

2000 W

W 3200 S

W 4500 N

STC 6760;S 3300 W

N 2000 E

3309: MARKET LAKE

SH 33

N. 1000 E. RD

US 20 EBL

US 20 WBL

E 3000 N

S 5500 W

EASTSIDE DRIVE

SH 33

EASTSIDE DRIVE

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