Total bridges
276
Public highway bridges in Lyon County
County profile · official public datasets
Lyon County, IA
276 public highway bridges tracked in the FHWA National Bridge Inventory: 38.8% rated Good, 38.4% Fair, 22.8% Poor.
- 276
- Public bridges
- 38.8%
- Good condition
- 22.8%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Lyon County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.
- 62nd
- of 99 on Poor share
- 22.8%
- Poor-condition share
- 276
- public highway bridges
- 1974
- 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.
Lyon County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Lyon County ranks #62 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 22.8%). Lyon County, Iowa contains 276 public highway bridges. Roughly 38.8% are rated “Good,” 38.4% “Fair,” and 22.8% “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.
Good condition
38.8%
107 of 276 rated 7-9
Fair condition
38.4%
106 of 276 rated 5-6
Poor condition
22.8%
63 of 276 rated 4 or below
In-state Poor-share rank
#62 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 276 NBI-tracked bridges by lowest applicable component rating.
Good 38.8% (107)
Fair 38.4% (106)
Poor 22.8% (63)
Lyon County's Poor-condition bridges carry 14,300 vehicle crossings a day
That is 13.5% of the county's reported daily bridge traffic on 22.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 227 crossings a day against 198 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 276 of 276 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
44.2% of Lyon County's bridges have passed the 50-year mark
122 of the 276 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 38.8% 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 7.1% of the county's Poor-condition bridge traffic
A26 (180TH ST) over BIG SIOUX RIVER, built 1977, carries 1,017 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 63-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 14,300 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Lyon County's bridges were built
276 bridges with a recorded construction year, grouped by decade
- 1900s
1900–1909
44 bridges
- 1920s 1
1920–1929
1 bridges
- 1930s 1
1930–1939
1 bridges
- 1940s 5
1940–1949
5 bridges
- 1950s 14
1950–1959
14 bridges
- 1960s
1960–1969
31 bridges
- 1970s
1970–1979
56 bridges
- 1980s 21
1980–1989
21 bridges
- 1990s 19
1990–1999
19 bridges
- 2000s 20
2000–2009
20 bridges
- 2010s
2010–2019
54 bridges
- 2020s 10
2020–2029
10 bridges
What this shows Construction peaked in the 1970s, when 56 of the county's bridges still in the inventory were built, which is 20.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1974, 5 years older than the Iowa average of 1979.
How Lyon County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Lyon County in number of bridges, with their condition splits. Its 22.8% Poor share is the 6th-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1983 is 9 years older.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Butler County | 289 | 58.1% | 26.6% | 15.2% | 1985 |
| Lyon County (this page) | 276 | 38.8% | 38.4% | 22.8% | 1974 |
| Kossuth County | 267 | 44.6% | 39% | 16.5% | 1987 |
| Bremer County | 266 | 51.9% | 36.1% | 12% | 1990 |
| Cerro Gordo County | 266 | 44% | 51.1% | 4.9% | 1975 |
| O'Brien County | 264 | 51.9% | 43.2% | 4.9% | 1976 |
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 Lyon 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 Lyon County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (276 bridges here).
- Hardin County, OH · 276 bridges
- Navajo County, AZ · 277 bridges
- Delaware County, IN · 277 bridges
- Porter County, IN · 277 bridges
Similar average build year
Nearest mean year-built outside IA (1974 here).
- Knox County, TN · avg 1974 · 588 bridges
- Summit County, OH · avg 1974 · 563 bridges
- Onondaga County, NY · avg 1974 · 472 bridges
- Orange County, NY · avg 1974 · 472 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (276)
LOCAL ROAD
PoorOver: ALLEN CREEK
098433002, Lyon, IA
Built 1900 Load: 23.0 t ADT: 26
LOCAL ROAD
PoorOver: KLONDIKE CREEK
099480104, Lyon, IA
Built 1900 Load: 24.4 t ADT: 41
FM
PoorOver: SMALL STREAM
099463002, Lyon, IA
Built 1972 Load: 24.5 t ADT: 240
FM
PoorOver: NELSON CREEK
098483204, Lyon, IA
Built 1966 Load: 24.7 t ADT: 789
FM
PoorOver: KLONDIKE CREEK
099482105, Lyon, IA
Built 1962 Load: 24.7 t ADT: 1,017
L14
PoorOver: TURNER CREEK
100441418, Lyon, IA
Built 1964 Load: 24.7 t ADT: 509
L14
PoorOver: DRY RUN CREEK
100442606, Lyon, IA
Built 1964 Load: 25.1 t ADT: 509
LOCAL ROAD
PoorOver: ALBERTSON CREEK
098471601, Lyon, IA
Built 1900 Load: 25.7 t ADT: 41
FM
PoorOver: DRY RUN CREEK
099452302, Lyon, IA
Built 1964 Load: 25.7 t ADT: 469
L14
PoorOver: TOM CREEK
100442304, Lyon, IA
Built 1964 Load: 25.9 t ADT: 509
LOCAL ROAD
PoorOver: EMERY CREEK
099443001, Lyon, IA
Built 1900 Load: 26.1 t ADT: 35
FM
PoorOver: MUD CREEK
098460406, Lyon, IA
Built 1961 Load: 26.3 t ADT: 509
FM
PoorOver: MUD CREEK
099470104, Lyon, IA
Built 1970 Load: 26.3 t ADT: 450
FM
PoorOver: ROCK RIVER
098462402, Lyon, IA
Built 1966 Load: 27.1 t ADT: 977
FM
PoorOver: ROCK RIVER
098463501, Lyon, IA
Built 1970 Load: 27.3 t ADT: 399
LOCAL ROAD
PoorOver: ROCK RIVER
099451501, Lyon, IA
Built 1968 Load: 27.3 t ADT: 337
LOCAL ROAD
PoorOver: RAT CREEK
098432801, Lyon, IA
Built 1900 Load: 28.8 t ADT: 21
LOCAL ROAD
PoorOver: SMALL STREAM
099462002, Lyon, IA
Built 1900 Load: 28.8 t ADT: 26
FM
PoorOver: RAT CREEK
098432202, Lyon, IA
Built 1966 Load: 30.4 t ADT: 199
FM
PoorOver: LITTLE OTTER CREEK
098433402, Lyon, IA
Built 1968 Load: 30.4 t ADT: 199
FM
PoorOver: MUD CREEK
099462003, Lyon, IA
Built 1968 Load: 30.4 t ADT: 688
FM
PoorOver: KLONDIKE CREEK
099481502, Lyon, IA
Built 1966 Load: 30.4 t ADT: 309
FM
PoorOver: MUD CREEK
100471301, Lyon, IA
Built 1970 Load: 30.4 t ADT: 290
FM
PoorOver: PLUM CREEK
098480102, Lyon, IA
Built 1968 Load: 32.3 t ADT: 210
FM
PoorOver: WEST RAT CREEK
098430102, Lyon, IA
Built 1965 Load: 33.0 t ADT: 230
FM
PoorOver: BLOOD RUN CREEK
100481902, Lyon, IA
Built 1971 Load: 36.9 t ADT: 180
Read our methodology - how this data is sourced, computed, and verified.
Related
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.