County profile · official public datasets

Sheridan County, MT

66 public highway bridges tracked in the FHWA National Bridge Inventory: 16.7% rated Good, 80.3% Fair, 3% Poor.

66
Public bridges: 16.7%
Good condition: 3%
Poor condition

The verdict

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

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

Top 18%
lowest Poor share in state: 3%
Poor-condition share: 66
public highway bridges: 1979
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.

Sheridan County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Sheridan County ranks #10 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3%). Sheridan County, Montana contains 66 public highway bridges. Roughly 16.7% are rated “Good,” 80.3% “Fair,” and 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 Sheridan County

Good condition

16.7%

11 of 66 rated 7-9

Fair condition

80.3%

53 of 66 rated 5-6

Poor condition

2 of 66 rated 4 or below

In-state Poor-share rank

#10 of 56

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

Condition distribution

Share of 66 NBI-tracked bridges by lowest applicable component rating.

Good

16.7% (11)

Fair

80.3% (53)

Poor

3% (2)

Sheridan County's Poor-condition bridges carry 375 vehicle crossings a day

That is 2.9% of the county's reported daily bridge traffic on 3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 188 crossings a day against 258 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 66 of 66 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

34.8% of Sheridan County's bridges have passed the 50-year mark

23 of the 66 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 16.7% 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 81.9% of the county's Poor-condition bridge traffic

S 5 over DAHL CREEK, built 1939, carries 307 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 375 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

3
1940s

2
1950s

5
1960s

3
1970s

17
1980s

23
1990s

5
2000s

5
2010s

3

What this shows Construction peaked in the 1980s, when 23 of the county's bridges still in the inventory were built, which is 34.8% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1979) matches the Montana average (1977).

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

The 5 Montana counties nearest Sheridan County in number of bridges, with their condition splits. Its 3% Poor share is the 3rd-lowest of these 6. Its average build year of 1979 against a peer-group mean of 1974 is 5 years newer.

Showing the 5 closest of 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Sheridan County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Granite County	73	37%	52.1%	11%	1974
Custer County	71	14.1%	84.5%	1.4%	1969
Glacier County	71	38%	56.3%	5.6%	1978
Deer Lodge County	68	27.9%	66.2%	5.9%	1973
Silver Bow County	68	16.2%	82.4%	1.5%	1974
Sheridan County (this page)	66	16.7%	80.3%	3%	1979

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

Similar inventory size

Nearest county inventories outside MT (66 bridges here).

Chugach County, AK · 66 bridges
Inyo County, CA · 66 bridges
Broomfield County, CO · 66 bridges
Cook County, GA · 66 bridges

Similar average build year

Nearest mean year-built outside MT (1979 here).

Pima County, AZ · avg 1979 · 1,150 bridges
Jefferson County, KY · avg 1979 · 662 bridges
Spartanburg County, SC · avg 1979 · 638 bridges
McPherson County, KS · avg 1979 · 586 bridges

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

All 66 Good 11 Fair 53 Poor 2

All bridges (66)

Sort:

Sheridan County Bridge Snapshot

Condition distribution

Sheridan County's Poor-condition bridges carry 375 vehicle crossings a day

34.8% of Sheridan County's bridges have passed the 50-year mark

One structure carries 81.9% of the county's Poor-condition bridge traffic

How Sheridan 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

All bridges (66)

DUTCH HENRY RD

TWIN BRIDGES RD

DUTCH HENRY RD

CHALK BUTTE RD

S REDSTONE RD

E REDSTONE RD

SHIPPE CANYON RD

WHISKEY RD

MANN RD

S 5

W RESERVE HWY

W RESERVE HWY

IRR - S 350

S 16

S 5

THREE CORNERS RD

OUTLOOK BENCH RD

DALEVIEW RD

SOO LINE RD

SOO LINE RD

HENDRICKSON HILL R

NINE MILE RD

DALEVIEW RD

DALEVIEW HILLS RD

DUTCH HENRY RD

COMERTOWN RD

MARRON CREEK RD

S DAGMAR RD

S DAGMAR RD

ROSE HILL RD

LONGFELLOW RD

CHERRY CREEK RD

E ANTELOPE RD

W RESERVE RD

SHIPPE CANYON RD

BOLSTER RD

BOLSTER RD

W LAKE RD

W LAKE RD

BERGH RD

W RESERVE RD

SINGLETREE RD

OLD MUDDY RD

WHITTISH HILL RD

S ARCHER RD

MIDBY RD

WHISKEY RD

S 374-OUTLOOK HWY

S 5

S 5

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