Plymouth County, IA

407 public highway bridges

Plymouth County Bridge Snapshot

Plymouth County, Iowa contains 407 public highway bridges in the FHWA National Bridge Inventory. Roughly 51.8% are rated “Good,” 24.6% “Fair,” 22.1% “Poor,” and 22.1% are classified as structurally deficient — the federal designation for spans whose deck, superstructure, or substructure has been rated 4 or below on the 0–9 NBI scale. Structurally deficient does not mean unsafe to cross; it means the bridge is on the priority list for repair or replacement.

Inspections in IA are conducted by certified engineers from the state Department of Transportation on a 24-month cycle, and results are reported back to the FHWA each spring. The list below shows every NBI-tracked bridge in the county, sorted by inventory load rating. Use the “Sort by” controls to surface the lowest-rated spans first, and click any row for full inspection history, traffic counts, and condition trends.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

407

Total Bridges

51.8%

Good

22.1%

Poor

22.1%

Structurally Deficient

Condition Distribution

Good

51.8% (211)

Fair

24.6% (100)

Poor

22.1% (90)

SD

22.1% (90)

All Bridges (407)

Sort:

SB US 75

Over: DRAINAGE DITCH

2.6 mi S of jct SR C44, Plymouth, IA

Built 1948 Load: 23.5 t ADT: 7,000

200TH ST

Over: BIG WHISKEY SLOUGH

092432601, Plymouth, IA

Built 1987 Load: 23.8 t ADT: 15

SUNSET AVE

Over: DD

091432302, Plymouth, IA

Built 1956 Load: 23.9 t ADT: 15

PIONEER AVE

Over: DRAINAGE

092440302, Plymouth, IA

Built 1991 Load: 23.9 t ADT: 30

FM C-60

Over: WEST FORK LITTLE SIOUX

090431001, Plymouth, IA

Built 1963 Load: 24.2 t ADT: 290

FM

Over: MINK CREEK

093462702, Plymouth, IA

Built 1961 Load: 24.5 t ADT: 628

220TH ST

Over: DRAINAGE

091440201, Plymouth, IA

Built 1900 Load: 25.9 t ADT: 15

FM

Over: PERRY CREEK

091472602, Plymouth, IA

Built 1970 Load: 26.0 t ADT: 1,028

170TH ST

Over: MINK CREEK

092460903, Plymouth, IA

Built 1934 Load: 26.0 t ADT: 60

FM

Over: PERRY CREEK

090472704, Plymouth, IA

Built 1970 Load: 26.3 t ADT: 2,134

QUORN RD

Over: WEST FORK LITTLE SIOUX

090442504, Plymouth, IA

Built 1965 Load: 26.8 t ADT: 40

FM

Over: CREEK

092433401, Plymouth, IA

Built 1976 Load: 27.0 t ADT: 848

MALLARD AVE

Over: SMALL NATURAL STREAM

093452329, Plymouth, IA

Built 1974 Load: 27.1 t ADT: 5

IA 404 SB

Over: FLOYD RIVER

0.4 mi. N of jct. IA 3, Plymouth, IA

Built 1957 Load: 27.5 t ADT: 2,410

IA 3

Over: STREAM

2.5 MI. E of US 75 (Bus.), Plymouth, IA

Built 1994 Load: 28.5 t ADT: 3,820

FM K-64

Over: DRAINAGE

090441702, Plymouth, IA

Built 1973 Load: 28.6 t ADT: 110

SB US 75

Over: STREAM

1.3 mi. N of SR C70, Plymouth, IA

Built 1948 Load: 29.0 t ADT: 7,500

FM

Over: BIG SIOUX RIVER

90948, Plymouth, IA

Built 1967 Load: 29.3 t ADT: 589

IA 140

Over: RATHBURN CREEK

3.3 mi S of SR C38, Plymouth, IA

Built 1964 Load: 29.5 t ADT: 970

FM K-49

Over: WHISKEY CREEK

091452702, Plymouth, IA

Built 1974 Load: 30.0 t ADT: 818

L-22

Over: LITTLE SIOUX RIVER

092432402, Plymouth, IA

Built 1974 Load: 30.0 t ADT: 139

FM C-38

Over: DRAINAGE

092453301, Plymouth, IA

Built 1977 Load: 30.0 t ADT: 1,615

SB US 75

Over: DRY CREEK

3.4 mi. N of jct. SR C60, Plymouth, IA

Built 1948 Load: 30.2 t ADT: 7,000

FM K-49

Over: PLYMOUTH CR

091450302, Plymouth, IA

Built 1974 Load: 30.2 t ADT: 1,236

FM

Over: JOHN'S CREEK

092443601, Plymouth, IA

Built 1976 Load: 30.2 t ADT: 1,157

FM

Over: INDIAN CREEK

093481202, Plymouth, IA

Built 1971 Load: 30.2 t ADT: 219

FM

Over: JOHN'S CREEK

090441201, Plymouth, IA

Built 1971 Load: 30.4 t ADT: 259

FM

Over: WILLOW CREEK

093442101, Plymouth, IA

Built 1967 Load: 30.4 t ADT: 589

FM

Over: WILLOW CREEK

093442102, Plymouth, IA

Built 1968 Load: 30.4 t ADT: 748

FM

Over: MINK CREEK

093462801, Plymouth, IA

Built 1967 Load: 30.6 t ADT: 190

SB US 75

Over: STREAM

1.3 mi. N of S.R. C-60, Plymouth, IA

Built 1948 Load: 31.6 t ADT: 7,000

FM K-18

Over: STREAM

091481104, Plymouth, IA

Built 1979 Load: 31.7 t ADT: 429

SB US 75

Over: DRY CREEK

1.9 mi. N of jct. SR C60, Plymouth, IA

Built 1948 Load: 32.2 t ADT: 7,000

SB US 75

Over: DRY CREEK

2.3 mi. N of SR C60, Plymouth, IA

Built 1948 Load: 32.3 t ADT: 7,000

SB US 75

Over: DRY CREEK

1.5 mi. S of SR C44, Plymouth, IA

Built 1948 Load: 32.3 t ADT: 7,000

FM

Over: DRAINAGE

091462303, Plymouth, IA

Built 1966 Load: 32.3 t ADT: 190

FM

Over: DRAINAGE DITCH

090432702, Plymouth, IA

Built 1932 Load: 32.7 t ADT: 139

FM

Over: PERRY CREEK

090470901, Plymouth, IA

Built 1940 Load: 32.7 t ADT: 159

FM

Over: DRAINAGE DITCH

091432101, Plymouth, IA

Built 1933 Load: 32.7 t ADT: 139

FM

Over: DRAINAGE

091461202, Plymouth, IA

Built 1966 Load: 32.7 t ADT: 190

FM

Over: MINNIE CREEK

092452702, Plymouth, IA

Built 1975 Load: 32.7 t ADT: 1,446

FM

Over: DRAINAGE

092483501, Plymouth, IA

Built 1960 Load: 32.7 t ADT: 669

200TH STREET

Over: FLOYD RIVER

F22030515, Plymouth, IA

Built 2007 Load: 32.7 t ADT: 8,224

FM K-49

Over: MUDDY CREEK

090451502, Plymouth, IA

Built 1974 Load: 33.0 t ADT: 509

FM

Over: SMALL

093472302, Plymouth, IA

Built 1978 Load: 33.0 t ADT: 688

IA 3

Over: FLOYD RIVER

1.0 mi. E of US 75, Plymouth, IA

Built 1981 Load: 33.2 t ADT: 4,270

LOCAL

Over: WILLOW CREEK

093443602, Plymouth, IA

Built 1967 Load: 33.9 t ADT: 319

OMEGA AVE

Over: CREEK

090441704, Plymouth, IA

Built 1900 Load: 34.1 t ADT: 5

IA 3

Over: MINK CREEK

0.4 mi W of SR K42, Plymouth, IA

Built 1954 Load: 35.7 t ADT: 1,420

IA 3

Over: WESTFIELD CREEK

0.2 mi. W of W jct. IA 12, Plymouth, IA

Built 1962 Load: 36.9 t ADT: 1,570

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

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Data sourced from official U.S. government datasets. See our methodology for details. Retrieved and formatted by PlainBridges Editorial

Reviewed byPlainbridges Editorial, Plain Bridges Editorial Team · June 6, 2026