County profile · official public datasets

Natrona County, WY

135 public highway bridges tracked in the FHWA National Bridge Inventory: 30.4% rated Good, 65.2% Fair, 4.4% Poor.

135
Public bridges: 30.4%
Good condition: 4.4%
Poor condition

The verdict

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

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

Top 35%
lowest Poor share in state: 4.4%
Poor-condition share: 135
public highway bridges: 1977
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.

Natrona County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Natrona County ranks #8 of 23 Wyoming counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.4%). Natrona County, Wyoming contains 135 public highway bridges. Roughly 30.4% are rated “Good,” 65.2% “Fair,” and 4.4% “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

135

Public highway bridges in Natrona County

Good condition

30.4%

41 of 135 rated 7-9

Fair condition

65.2%

88 of 135 rated 5-6

Poor condition

4.4%

6 of 135 rated 4 or below

In-state Poor-share rank

#8 of 23

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

Condition distribution

Share of 135 NBI-tracked bridges by lowest applicable component rating.

Good

30.4% (41)

Fair

65.2% (88)

Poor

4.4% (6)

Natrona County's Poor-condition bridges carry 12,969 vehicle crossings a day

That is 2.7% of the county's reported daily bridge traffic on 4.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,162 crossings a day against 2,867 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 135 of 135 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

45.9% of Natrona County's bridges have passed the 50-year mark

62 of the 135 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 30.4% 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 61.5% of the county's Poor-condition bridge traffic

Hereford Lane over I-25, built 1960, carries 7,970 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 6-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 12,969 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

3
1940s

2
1950s

15
1960s

27
1970s

29
1980s

28
1990s

10
2000s

12
2010s

6
2020s

3

What this shows Construction peaked in the 1970s, when 29 of the county's bridges still in the inventory were built, which is 21.5% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1977) matches the Wyoming average (1976).

How Natrona County compares with Wyoming's closest counties by inventory size

The 5 Wyoming counties nearest Natrona County in number of bridges, with their condition splits. Its 4.4% Poor share is the 2nd-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1978 is in line with the group.

Showing the 5 closest of 22 Wyoming counties eligible for comparison.

Bridge inventory size and condition shares for Natrona County and the 5 Wyoming counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Converse County	137	14.6%	72.3%	13.1%	1974
Natrona County (this page)	135	30.4%	65.2%	4.4%	1977
Uinta County	132	18.9%	69.7%	11.4%	1976
Lincoln County	129	31.8%	62.8%	5.4%	1985
Albany County	124	33.1%	65.3%	1.6%	1976
Teton County	119	31.9%	55.5%	12.6%	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 Natrona 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 Natrona County, both outside Wyoming so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside WY (135 bridges here).

Nevada County, CA · 135 bridges
Meriwether County, GA · 135 bridges
Steuben County, IN · 135 bridges
Warren County, IN · 135 bridges

Similar average build year

Nearest mean year-built outside WY (1977 here).

San Diego County, CA · avg 1977 · 1,632 bridges
King County, WA · avg 1977 · 1,238 bridges
Riverside County, CA · avg 1977 · 1,117 bridges
Shelby County, TN · avg 1977 · 1,077 bridges

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

All 135 Good 41 Fair 88 Poor 6

All bridges (135)

Sort:

Natrona County Bridge Snapshot

Condition distribution

Natrona County's Poor-condition bridges carry 12,969 vehicle crossings a day

45.9% of Natrona County's bridges have passed the 50-year mark

One structure carries 61.5% of the county's Poor-condition bridge traffic

How Natrona County compares with Wyoming'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 (135)

Na Cnty Rd 408

US 20

Na Cnty Rd 201

I-25 SBL

I-25 NBL

I-25 NBL

I-25 SBL

Na Cnty Rd 101

Na Cnty Rd 407

WYO 258 (Wyo Blvd)

WYO 387

US 20

I-25 NBL

I-25 SBL

US 20

I-25 SBL

I-25 NBL

I-25 NBL

US 20

VeteransCemeteryRd

I-25 SBL

US 20

WYO 259

WYO 257

Na Cnty Rd 403

WYO 259

WYO 259

Na Cnty Rd 305

Na Cnty Rd 410

I-25 NBL

I-25 SBL

Na Cnty Rd 308

WYO 257

WYO 220

WYO 256

I-25 SBL

I-25 NBL

US 20

I-25 Service Road

I-25 Service Road

US 20/26/87 EBL

US 20/26/87 WBL

WYO 253

I-25 NBL

I-25 SBL

Unnamed Road

US 20

I-25 NBL

Na Cnty Rd 316

W 25th Street

Related