Total bridges
151
Public highway bridges in Clay County
County profile · official public datasets
Clay County, IA
151 public highway bridges tracked in the FHWA National Bridge Inventory: 35.8% rated Good, 54.3% Fair, 9.9% Poor.
- 151
- Public bridges
- 35.8%
- Good condition
- 9.9%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Clay County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 19%
- lowest Poor share in state
- 9.9%
- Poor-condition share
- 151
- public highway bridges
- 1982
- 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.
Clay County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Clay County ranks #19 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.9%). Clay County, Iowa contains 151 public highway bridges. Roughly 35.8% are rated “Good,” 54.3% “Fair,” and 9.9% “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
35.8%
54 of 151 rated 7-9
Fair condition
54.3%
82 of 151 rated 5-6
Poor condition
9.9%
15 of 151 rated 4 or below
In-state Poor-share rank
#19 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 151 NBI-tracked bridges by lowest applicable component rating.
Good 35.8% (54)
Fair 54.3% (82)
Poor 9.9% (15)
Clay County's Poor-condition bridges carry 7,528 vehicle crossings a day
That is 7.2% of the county's reported daily bridge traffic on 9.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 502 crossings a day against 796 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 151 of 151 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
31.1% of Clay County's bridges have passed the 50-year mark
47 of the 151 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 35.8% 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 34.2% of the county's Poor-condition bridge traffic
FM 340TH ST over LITTLE SIOUX RIVER, built 1963, carries 2,573 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 15-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 7,528 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Clay County's bridges were built
151 bridges with a recorded construction year, grouped by decade
- 1900s 3
1900–1909
3 bridges
- 1910s 4
1910–1919
4 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 4
1930–1939
4 bridges
- 1940s 1
1940–1949
1 bridges
- 1950s 3
1950–1959
3 bridges
- 1960s
1960–1969
22 bridges
- 1970s
1970–1979
28 bridges
- 1980s
1980–1989
12 bridges
- 1990s
1990–1999
28 bridges
- 2000s
2000–2009
29 bridges
- 2010s 11
2010–2019
11 bridges
- 2020s 4
2020–2029
4 bridges
What this shows Construction peaked in the 2000s, when 29 of the county's bridges still in the inventory were built, which is 19.2% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1982) matches the Iowa average (1979).
How Clay County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Clay County in number of bridges, with their condition splits. Its 9.9% Poor share is the 1st-lowest of these 6. Its average build year of 1982 against a peer-group mean of 1979 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Jefferson County | 157 | 43.9% | 37.6% | 18.5% | 1983 |
| Buena Vista County | 156 | 35.9% | 32.7% | 31.4% | 1979 |
| Van Buren County | 156 | 23.7% | 44.9% | 31.4% | 1975 |
| Louisa County | 151 | 33.1% | 50.3% | 16.6% | 1980 |
| Clay County (this page) | 151 | 35.8% | 54.3% | 9.9% | 1982 |
| Muscatine County | 144 | 34.7% | 43.8% | 21.5% | 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 Clay 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 Clay County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (151 bridges here).
- Randolph County, AR · 151 bridges
- Pasco County, FL · 151 bridges
- St. Lucie County, FL · 151 bridges
- Hall County, GA · 151 bridges
Similar average build year
Nearest mean year-built outside IA (1982 here).
- Oklahoma County, OK · avg 1982 · 1,216 bridges
- Jackson County, MO · avg 1982 · 930 bridges
- Milwaukee County, WI · avg 1982 · 893 bridges
- Champaign County, IL · avg 1982 · 727 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (151)
450TH ST
FairOver: STREAM
094370501, Clay, IA
Built 1949 Load: 20.7 t ADT: 15
140TH AVE
FairOver: OCHEYEDAN RIVER
096381102, Clay, IA
Built 1963 Load: 21.7 t ADT: 153
390TH ST
FairOver: OVERFLOW LITTLE SIOUX R
095360201, Clay, IA
Built 1955 Load: 22.7 t ADT: 40
420TH ST
FairOver: ELK CREEK
095352001, Clay, IA
Built 1978 Load: 23.0 t ADT: 11
330TH ST
FairOver: STONY CREEK
096370603, Clay, IA
Built 1965 Load: 23.7 t ADT: 41
US 18
FairOver: STONY CREEK
5.3 mi. W of W jct US 71, Clay, IA
Built 1915 Load: 24.1 t ADT: 2,700
US 18
FairOver: LOST ISLAND OUTLET
1.0 mi. E of jct. SR M54, Clay, IA
Built 1931 Load: 24.4 t ADT: 4,270
FM 350TH ST
FairOver: BIG MEADOW CREEK
096361501, Clay, IA
Built 1963 Load: 24.9 t ADT: 878
FM 300TH ST
FairOver: DRAINAGE DITCH
097352201, Clay, IA
Built 1963 Load: 25.2 t ADT: 469
US 71
FairOver: WILLOW CREEK
3.4 mi. N of N jct IA 10, Clay, IA
Built 1923 Load: 25.9 t ADT: 3,940
IA 10
FairOver: DRAINAGE DITCH
3.2 mi. W of jct. SR M36, Clay, IA
Built 1932 Load: 26.0 t ADT: 710
FM 130TH AVE
FairOver: WILLOW CREEK
095381502, Clay, IA
Built 1964 Load: 26.0 t ADT: 619
FM 190TH AVE
FairOver: PRAIRIE CREEK
096373402, Clay, IA
Built 1964 Load: 26.6 t ADT: 818
FM 310TH AVE
FairOver: L TRUMBULL OUTLET
097352702, Clay, IA
Built 1970 Load: 26.6 t ADT: 968
FM 270TH AVE
FairOver: MEADOW CREEK
097361302, Clay, IA
Built 1968 Load: 26.6 t ADT: 50
US 18
FairOver: LITTLE SIOUX OVERFLOW
3.6 mi. E of E jct. US 71, Clay, IA
Built 1931 Load: 27.7 t ADT: 4,170
180TH AVE
FairOver: PRAIRIE CREEK
095370402, Clay, IA
Built 2008 Load: 27.7 t ADT: 21
FM 260TH AVE
FairOver: LITTLE SIOUX RIVER
095363502, Clay, IA
Built 1969 Load: 27.9 t ADT: 71
190TH AVE
FairOver: WILLOW CREEK
094370302, Clay, IA
Built 1978 Load: 28.6 t ADT: 72
470TH ST
FairOver: MONTGOMERY CREEK
094361403, Clay, IA
Built 1998 Load: 29.5 t ADT: 30
225TH ST
FairOver: WILLOW CREEK
094360704, Clay, IA
Built 1978 Load: 29.7 t ADT: 26
FM 150TH AVE
FairOver: WILLOW CREEK
095382502, Clay, IA
Built 1973 Load: 29.7 t ADT: 180
270TH ST
FairOver: STONY CREEK
097380301, Clay, IA
Built 1976 Load: 29.7 t ADT: 26
FM 160TH AVE
FairOver: OCHEYEDAN RIVER
096370702, Clay, IA
Built 1981 Load: 30.2 t ADT: 40
FM 260TH AVE
FairOver: OVERFLOW LITTLE SIOUX
094360202, Clay, IA
Built 1966 Load: 30.3 t ADT: 71
180TH AVE
FairOver: WILLOW CREEK
094370402, Clay, IA
Built 1979 Load: 30.4 t ADT: 50
FM 100TH AVE
FairOver: BR OCHEYEDAN R
096380602, Clay, IA
Built 1967 Load: 30.4 t ADT: 359
270TH ST
FairOver: BIG MEADOW CK
097350601, Clay, IA
Built 1976 Load: 30.4 t ADT: 20
340TH ST
FairOver: BIG MEADOW CREEK
096361001, Clay, IA
Built 1981 Load: 30.6 t ADT: 105
230TH AVE
FairOver: DD #28
097362902, Clay, IA
Built 1979 Load: 30.6 t ADT: 123
350TH ST
FairOver: OVERFLOW MEADOW CREEK
096361501, Clay, IA
Built 1976 Load: 31.1 t ADT: 878
FM 300TH ST
FairOver: LITTLE MEADOW CK
097362101, Clay, IA
Built 1989 Load: 31.1 t ADT: 369
310TH ST
FairOver: LITTLE MUDDY CREEK
097362801, Clay, IA
Built 1991 Load: 31.1 t ADT: 21
420TH ST
FairOver: WILLOW CREEK
095382201, Clay, IA
Built 1978 Load: 32.3 t ADT: 11
290TH AVE
FairOver: STREAM
096352002, Clay, IA
Built 1994 Load: 32.3 t ADT: 103
380TH ST
FairOver: PRAIRIE CK
096363301, Clay, IA
Built 1977 Load: 32.3 t ADT: 30
330TH ST
FairOver: STREAM
096380201, Clay, IA
Built 1900 Load: 32.3 t ADT: 123
FM 350TH ST
FairOver: DRAINAGE
096381701, Clay, IA
Built 1972 Load: 32.3 t ADT: 908
FM 100TH AVE
FairOver: STREAM
096381802, Clay, IA
Built 1972 Load: 32.3 t ADT: 529
310TH ST
FairOver: MEADOW CREEK
097362601, Clay, IA
Built 1999 Load: 32.4 t ADT: 30
240TH AVE
FairOver: LITTLE MEADOWS
097362802, Clay, IA
Built 1999 Load: 32.4 t ADT: 123
FM 280TH ST
FairOver: STONEY CREEK
097381001, Clay, IA
Built 1965 Load: 32.4 t ADT: 270
US 18
FairOver: LITTLE SIOUX RIVER
2.1 mi. W of W Jct US 71, Clay, IA
Built 1930 Load: 32.5 t ADT: 2,560
US 18
FairOver: DRAINAGE DITCH
At the jct of SR N14, Clay, IA
Built 1965 Load: 32.7 t ADT: 4,270
490TH ST
FairOver: MONTGOMERY CREEK
094353001, Clay, IA
Built 1990 Load: 32.7 t ADT: 46
190TH AVE
FairOver: STREAM
094371002, Clay, IA
Built 1999 Load: 32.7 t ADT: 46
225TH AVE
FairOver: SMALL STREAM
095360604, Clay, IA
Built 1978 Load: 32.7 t ADT: 81
FM 440TH ST
FairOver: SMALL
095373201, Clay, IA
Built 1988 Load: 32.7 t ADT: 469
FM 400TH ST
FairOver: WILLOW CREEK
095380801, Clay, IA
Built 1968 Load: 32.7 t ADT: 797
370TH ST
FairOver: STREAM
096352601, Clay, IA
Built 2001 Load: 32.7 t ADT: 47
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.