Total bridges
167
Public highway bridges in Mitchell County
County profile · official public datasets
Mitchell County, IA
167 public highway bridges tracked in the FHWA National Bridge Inventory: 47.3% rated Good, 42.5% Fair, 10.2% Poor.
- 167
- Public bridges
- 47.3%
- Good condition
- 10.2%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Mitchell County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 20%
- lowest Poor share in state
- 10.2%
- Poor-condition share
- 167
- public highway bridges
- 1980
- 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.
Mitchell County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Mitchell County ranks #20 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10.2%). Mitchell County, Iowa contains 167 public highway bridges. Roughly 47.3% are rated “Good,” 42.5% “Fair,” and 10.2% “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
47.3%
79 of 167 rated 7-9
Fair condition
42.5%
71 of 167 rated 5-6
Poor condition
10.2%
17 of 167 rated 4 or below
In-state Poor-share rank
#20 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 167 NBI-tracked bridges by lowest applicable component rating.
Good 47.3% (79)
Fair 42.5% (71)
Poor 10.2% (17)
Mitchell County's Poor-condition bridges carry 3,938 vehicle crossings a day
That is 6.6% of the county's reported daily bridge traffic on 10.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 232 crossings a day against 392 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 167 of 167 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
37.1% of Mitchell County's bridges have passed the 50-year mark
62 of the 167 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 47.3% 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 25.7% of the county's Poor-condition bridge traffic
LANCER AVE over SMALL NATURAL STREAM, built 1925, carries 1,011 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 17-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 3,938 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Mitchell County's bridges were built
167 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1910s 2
1910–1919
2 bridges
- 1920s 6
1920–1929
6 bridges
- 1930s 8
1930–1939
8 bridges
- 1940s 1
1940–1949
1 bridges
- 1950s 12
1950–1959
12 bridges
- 1960s 10
1960–1969
10 bridges
- 1970s
1970–1979
44 bridges
- 1980s
1980–1989
23 bridges
- 1990s
1990–1999
19 bridges
- 2000s
2000–2009
21 bridges
- 2010s 16
2010–2019
16 bridges
- 2020s 4
2020–2029
4 bridges
What this shows Construction peaked in the 1970s, when 44 of the county's bridges still in the inventory were built, which is 26.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1980) matches the Iowa average (1979).
How Mitchell County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Mitchell County in number of bridges, with their condition splits. Its 10.2% Poor share is the 1st-lowest of these 6. Its average build year of 1980 against a peer-group mean of 1977 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Union County | 169 | 30.2% | 37.3% | 32.5% | 1978 |
| Clarke County | 168 | 27.4% | 41.1% | 31.5% | 1977 |
| Greene County | 168 | 35.1% | 50% | 14.9% | 1973 |
| Mitchell County (this page) | 167 | 47.3% | 42.5% | 10.2% | 1980 |
| Davis County | 165 | 44.8% | 29.7% | 25.5% | 1985 |
| Hamilton County | 165 | 39.4% | 40% | 20.6% | 1970 |
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 Mitchell 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 Mitchell County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (167 bridges here).
- Cherokee County, AL · 167 bridges
- Garfield County, CO · 167 bridges
- Ness County, KS · 167 bridges
- Gratiot County, MI · 167 bridges
Similar average build year
Nearest mean year-built outside IA (1980 here).
- Tulsa County, OK · avg 1980 · 1,135 bridges
- Miami-Dade County, FL · avg 1980 · 1,057 bridges
- Pulaski County, AR · avg 1980 · 721 bridges
- McLennan County, TX · avg 1980 · 714 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (17)
LAWRENCE ST
PoorOver: DRAINAGE
000000000, Mitchell, IA
Built 1950 Load: 0.0 t ADT: 167
PRIMROSE AVE
PoorOver: CREEK
100161604, Mitchell, IA
Built 1950 Load: 0.0 t ADT: 20
PRIMROSE AVE
PoorOver: LITTLE CEDAR RIVER
099161604, Mitchell, IA
Built 1908 Load: 0.0 t ADT: 33
VALLEY AVE
PoorOver: CREEK
098151502, Mitchell, IA
Built 1960 Load: 10.9 t ADT: 11
TIMBER AVE
PoorOver: WAPSIPINICON RIVER
100151702, Mitchell, IA
Built 1959 Load: 13.2 t ADT: 29
WALNUT AVE
PoorOver: WAPSIPINICON RIVER
099151402, Mitchell, IA
Built 1940 Load: 16.5 t ADT: 462
LANCER AVE
PoorOver: SMALL NATURAL STREAM
099172406, Mitchell, IA
Built 1925 Load: 16.7 t ADT: 1,011
320TH
PoorOver: LITTLE CEDAR RIVER
097161303, Mitchell, IA
Built 1931 Load: 17.1 t ADT: 226
420TH
PoorOver: BURR OAK CREEK
099172501, Mitchell, IA
Built 1966 Load: 18.3 t ADT: 15
430TH
PoorOver: CREEK
099162301, Mitchell, IA
Built 1953 Load: 19.0 t ADT: 403
400TH
PoorOver: BEAVER CREEK
098160105, Mitchell, IA
Built 1915 Load: 20.0 t ADT: 29
440TH
PoorOver: DEER CREEK
099181601, Mitchell, IA
Built 1950 Load: 20.1 t ADT: 59
320TH
PoorOver: FISH CREEK
097161301, Mitchell, IA
Built 1965 Load: 29.9 t ADT: 226
390TH
PoorOver: ROCK CREEK
098180701, Mitchell, IA
Built 1973 Load: 30.8 t ADT: 216
RAMPART AVE
PoorOver: SMALL STREAM
099161202, Mitchell, IA
Built 1974 Load: 30.8 t ADT: 59
480TH
PoorOver: SMALL STREAM
100182601, Mitchell, IA
Built 1984 Load: 35.4 t ADT: 216
S70 450TH ST
PoorOver: DEER CREEK
099180801, Mitchell, IA
Built 1931 Load: 37.4 t ADT: 756
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.