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

66

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

3%

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.

When Sheridan County's bridges were built

66 bridges with a recorded construction year, grouped by decade

bridges

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).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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 Poor
Granite County 73 11%
Custer County 71 1.4%
Glacier County 71 5.6%
Deer Lodge County 68 5.9%
Silver Bow County 68 1.5%
Sheridan County (this page) 66 3%

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).

Similar average build year

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

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)

S 5

Fair

Over: MARRON CREEK

1M E PLENTYWOOD, Sheridan, MT

Built 1983 Load: 86.2 t ADT: 1,481

S 5

Fair

Over: PLENTYWOOD CREEK

5M W PLENTYWOOD, Sheridan, MT

Built 2001 Load: 89.8 t ADT: 585

S 16

Fair

Over: ATOR CREEK

3M NW ANTELOPE, Sheridan, MT

Built 1984 Load: 99.9 t ADT: 1,481

E LAKE HWY

Good

Over: LAKE CREEK 060

9M E MEDICINE LAKE, Sheridan, MT

Built 1965 Load: 27.2 t ADT: 108

S 5

Good

Over: ANTELOPE CREEK

2M S ANTELOPE, Sheridan, MT

Built 1986 Load: 27.2 t ADT: 1,125

BEAVER CREEK RD

Good

Over: BEAVER CREEK 008

11M N REDSTONE, Sheridan, MT

Built 1993 Load: 29.0 t ADT: 100

SANDHILLS RD

Good

Over: SAND CREEK 057

15M E MEDICINE LAKE, Sheridan, MT

Built 1988 Load: 32.7 t ADT: 100

LAKE CREEK RD

Good

Over: LAKE CREEK 078

20M E PLENTYWOOD, Sheridan, MT

Built 1983 Load: 32.7 t ADT: 100

LOST CREEK RD

Good

Over: LOST CREEK 050

2M S HOMESTEAD, Sheridan, MT

Built 1991 Load: 32.7 t ADT: 100

S 5

Good

Over: REDSTONE CREEK

2M SE REDSTONE, Sheridan, MT

Built 2011 Load: 32.7 t ADT: 508

S 5

Good

Over: MCCOY CREEK

3M W PLENTYWOOD, Sheridan, MT

Built 2001 Load: 32.7 t ADT: 585

MIDBY RD

Good

Over: BIG MUDDY CREEK 024

7M W PLENTYWOOD, Sheridan, MT

Built 1987 Load: 35.4 t ADT: 22

S ARCHER RD

Good

Over: BIG MUDDY CREEK 016

7M SE REDSTONE, Sheridan, MT

Built 2004 Load: 36.3 t ADT: 17

COUNTY ROAD 468

Good

Over: DIVERSION CANAL 079

1M W MEDICINE LAKE, Sheridan, MT

Built 2004 Load: 38.3 t ADT: 68

W LAKE RD

Poor

Over: BIG MUDDY CREEK 046

3M W MEDICINE LAKE, Sheridan, MT

Built 1950 Load: 18.1 t ADT: 68

S 5

Poor

Over: DAHL CREEK

12M SW WESTBY, Sheridan, MT

Built 1939 Load: 23.6 t ADT: 307

Read our methodology - how this data is sourced, computed, and verified.

Related

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.