County profile · official public datasets

Madison County, MT

97 public highway bridges tracked in the FHWA National Bridge Inventory: 32% rated Good, 56.7% Fair, 11.3% Poor.

97
Public bridges: 32%
Good condition: 11.3%
Poor condition

The verdict

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

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

48th
of 56 on Poor share: 11.3%
Poor-condition share: 97
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 #48 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 11.3%). Madison County, Montana contains 97 public highway bridges. Roughly 32% are rated “Good,” 56.7% “Fair,” and 11.3% “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 Madison County

Good condition

32%

31 of 97 rated 7-9

Fair condition

56.7%

55 of 97 rated 5-6

Poor condition

11.3%

11 of 97 rated 4 or below

In-state Poor-share rank

#48 of 56

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

Condition distribution

Share of 97 NBI-tracked bridges by lowest applicable component rating.

Good

32% (31)

Fair

56.7% (55)

Poor

11.3% (11)

Madison County's Poor-condition bridges carry 4,031 vehicle crossings a day

That is 5% of the county's reported daily bridge traffic on 11.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 366 crossings a day against 697 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 97 of 97 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

43.3% of Madison County's bridges have passed the 50-year mark

42 of the 97 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% 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 56% of the county's Poor-condition bridge traffic

S 287 over WEBER IRRIGATION CANAL, built 1950, carries 2,257 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 11-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 4,031 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1920s

1
1930s

2
1940s

9
1950s

12
1960s

7
1970s

15
1980s

5
1990s

10
2000s

19
2010s

14
2020s

2

What this shows Construction peaked in the 2000s, when 19 of the county's bridges still in the inventory were built, which is 19.6% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1981) matches the Montana average (1977).

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

The 5 Montana counties nearest Madison County in number of bridges, with their condition splits. Its 11.3% Poor share is the 5th-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 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Madison County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Blaine County	102	33.3%	56.9%	9.8%	1969
Phillips County	101	13.9%	69.3%	16.8%	1972
Richland County	97	28.9%	68%	3.1%	1988
Madison County (this page)	97	32%	56.7%	11.3%	1981
Pondera County	96	51%	44.8%	4.2%	1975
Sweet Grass County	94	28.7%	66%	5.3%	1977

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 Montana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MT (97 bridges here).

Forsyth County, GA · 97 bridges
Elmore County, ID · 97 bridges
Mason County, KY · 97 bridges
Swift County, MN · 97 bridges

Similar average build year

Nearest mean year-built outside MT (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 97 Good 31 Fair 55 Poor 11

Fair-condition bridges (55)

Sort:

Madison County Bridge Snapshot

Condition distribution

Madison County's Poor-condition bridges carry 4,031 vehicle crossings a day

43.3% of Madison County's bridges have passed the 50-year mark

One structure carries 56% of the county's Poor-condition bridge traffic

How Madison 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 (55)

CARMICHAEL ROAD

SUNDANCE BENCH RD

BURMA RD

FDR #1205

S 87

RUBY ROAD

S BOULDER RD

NO DATA ENTERED

FISHING ACCESS

BURMA RD

RUBY-CENTENNTIAL

KOUNTZ RD

S 359

CLIFF LAKE RD

S 287

TOLEDO MINE ROAD

S 287

S 41

S 41

MELROSE RD

S 359

PRIMROSE LN

I 15

S WILLOW CREEK RD

DUNCAN DISTRICT RD

US 287

SPANISH CREEK ROAD

US 287

JACK CREEK RD

I 15

US 287

MT 41

S 84

I 15

I 15

NO DATA ENTERED

S 287

I 15

KOUNTZ RD

LEWIS LN

COTTONWOOD CREEK R

SWEETWATER RD

PRIMROSE LN

LEDFORD CREEK RD

JACK CR BENCH RD

I 15

JOHNNY RIDGE RD

S 359

LAKE RD-COUNTY RD

I 15

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