Natrona County, WY

138 public highway bridges

Natrona County Bridge Snapshot

Natrona County, Wyoming contains 138 public highway bridges in the FHWA National Bridge Inventory. Roughly 22.5% are rated “Good,” 47.1% “Fair,” 3.6% “Poor,” and 3.6% 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 WY 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.

138

Total Bridges

22.5%

Good

3.6%

Poor

3.6%

Structurally Deficient

Condition Distribution

Good

22.5% (31)

Fair

47.1% (65)

Poor

3.6% (5)

SD

3.6% (5)

All Bridges (138)

Sort:

WYO 487

Over: Bates Creek

Medicine Bow - Jt WYO 220, Natrona, WY

Built 1981 Load: 30.8 t ADT: 832

US 20/26 Conn. WBL

Over: BNSF / Casper Creek

Casper, Natrona, WY

Built 1961 Load: 31.8 t ADT: 5,629

US 20/26 Conn. EBL

Over: BNSF / Casper Creek

Casper, Natrona, WY

Built 1961 Load: 31.8 t ADT: 5,821

WYO 220

Over: North Platte River

Casper, Natrona, WY

Built 1969 Load: 32.4 t ADT: 14,658

I-25 Service Road

Over: Horse Creek

Bar Nunn North, Natrona, WY

Built 1950 Load: 32.7 t ADT: 85

WYO 387

Over: Bothwell Draw

Jct I-25 - Reno Jct, Natrona, WY

Built 1952 Load: 32.7 t ADT: 427

WYO 220

Over: Horse Creek

Muddy Gap Jct-WYO 487 Jct, Natrona, WY

Built 1970 Load: 32.7 t ADT: 2,285

WYO 220

Over: Cottonwood Creek

WYO 487 Jct - Casper, Natrona, WY

Built 1965 Load: 32.7 t ADT: 3,604

WYO 220

Over: BNSF Railway

Casper, Natrona, WY

Built 1969 Load: 32.7 t ADT: 14,551

US 20

Over: South Fork Powder River

Casper - Shoshoni, Natrona, WY

Built 1973 Load: 32.7 t ADT: 2,446

Na Cnty Rd 125

Over: Middle Fork Casper Creek

19 Miles N.W. Of Casper, Natrona, WY

Built 1973 Load: 32.7 t ADT: 124

Na Cnty Rd 106

Over: South Fork Powder River

3 Miles N. Of Powder Rive, Natrona, WY

Built 1979 Load: 32.7 t ADT: 20

WYO 220

Over: Unnamed Draw

Muddy Gap-Casper, Natrona, WY

Built 1970 Load: 32.7 t ADT: 3,604

WYO 220

Over: Garden Creek

Casper, Natrona, WY

Built 2001 Load: 32.7 t ADT: 26,189

Na Cnty Rd 403

Over: Stinking Creek

23 Mi Sw Of Casper, Natrona, WY

Built 2007 Load: 32.7 t ADT: 2

WYO 387

Over: Salt Creek

Jct I-25 - Reno Jct, Natrona, WY

Built 1952 Load: 33.6 t ADT: 427

WYO 220

Over: Rush Creek

Muddy Gap Jct-WYO 487 Jct, Natrona, WY

Built 1968 Load: 33.6 t ADT: 1,771

WYO 220

Over: Bates Creek

Muddy Gap Jct-WYO 487 Jct, Natrona, WY

Built 1963 Load: 33.6 t ADT: 3,066

US 20

Over: Casper Creek

Casper, Natrona, WY

Built 1977 Load: 33.6 t ADT: 11,513

I-25 SBL

Over: Castle Creek

Casper - Kaycee, Natrona, WY

Built 1980 Load: 33.6 t ADT: 1,464

I-25 NBL

Over: Castle Creek

Casper - Kaycee, Natrona, WY

Built 1980 Load: 33.6 t ADT: 1,515

Na Cnty Rd 408

Over: North Platte River

7.5 Miles S.W. Of Alcova, Natrona, WY

Built 1957 Load: 33.6 t ADT: 83

US 20

Over: Middle Fork Casper Creek

Casper-Shoshoni, Natrona, WY

Built 1984 Load: 33.6 t ADT: 2,908

Na Cnty Rd 201

Over: Poison Spider Creek

11 Miles West Of Casper, Natrona, WY

Built 1991 Load: 33.6 t ADT: 937

I-25 SBL

Over: Machinery Pass

Casper - Kaycee, Natrona, WY

Built 1980 Load: 34.5 t ADT: 1,464

Na Cnty Rd 101

Over: Badwater Creek

23 Miles N.W. Of Waltman, Natrona, WY

Built 1984 Load: 34.5 t ADT: 12

Na Cnty Rd 407

Over: North Platte River

Alcova, Natrona, WY

Built 2019 Load: 35.3 t ADT: 63

WYO 258 (Wyo Blvd)

Over: North Platte River

Casper, Natrona, WY

Built 1974 Load: 35.4 t ADT: 11,674

WYO 387

Over: Coal Draw

Midwest - Reno Jct, Natrona, WY

Built 1977 Load: 35.4 t ADT: 2,168

US 20

Over: Middle Fork Casper Creek

Casper-Shoshoni, Natrona, WY

Built 1984 Load: 35.4 t ADT: 2,908

I-25 NBL

Over: Machinery Pass

Douglas - Casper, Natrona, WY

Built 1966 Load: 36.3 t ADT: 4,193

I-25 SBL

Over: Machinery Pass

Douglas - Casper, Natrona, WY

Built 1966 Load: 36.3 t ADT: 4,702

US 20

Over: C and NW Railroad

Casper, Natrona, WY

Built 1977 Load: 36.3 t ADT: 11,513

I-25 SBL

Over: Machinery Pass

Casper - Kaycee, Natrona, WY

Built 1980 Load: 36.3 t ADT: 1,464

I-25 NBL

Over: Machinery Pass

Casper - Kaycee, Natrona, WY

Built 1980 Load: 36.3 t ADT: 1,515

I-25 NBL

Over: Machinery Pass

Casper - Kaycee, Natrona, WY

Built 1980 Load: 36.6 t ADT: 1,515

US 20

Over: Middle Fork Casper Creek

Casper-Shoshoni, Natrona, WY

Built 1984 Load: 38.1 t ADT: 2,908

VeteransCemeteryRd

Over: North Platte River

T34N R079W S36, Natrona, WY

Built 1985 Load: 38.1 t ADT: 100

I-25 SBL

Over: North Platte River

Casper Marginal, Natrona, WY

Built 1956 Load: 41.4 t ADT: 13,026

US 20

Over: Wyatt Draw

Casper - Shoshoni, Natrona, WY

Built 1973 Load: 42.6 t ADT: 2,446

WYO 259

Over: East Teapot Creek

Casper-Midwest Road, Natrona, WY

Built 1999 Load: 42.6 t ADT: 3,812

WYO 257

Over: North Platte River

Casper Streets, Natrona, WY

Built 2013 Load: 43.1 t ADT: 1,066

Na Cnty Rd 403

Over: Bolton Creek

20 Mi. S.W. Of Casper, Natrona, WY

Built 1994 Load: 43.5 t ADT: 2

WYO 259

Over: Teapot Creek

I-25 - Midwest Road, Natrona, WY

Built 1999 Load: 44.5 t ADT: 3,910

WYO 259

Over: Salt Creek

Jct I-25 - Midwest, Natrona, WY

Built 2000 Load: 44.5 t ADT: 3,910

Na Cnty Rd 305

Over: North Platte River

Robertson Rd., Natrona, WY

Built 2002 Load: 45.0 t ADT: 7,337

Na Cnty Rd 410

Over: Sweetwater River

43 Miles S.W. Of Casper, Natrona, WY

Built 1984 Load: 45.4 t ADT: 11

Na Cnty Rd 308

Over: North Platte River

Bessemer Road, CN1-308, Natrona, WY

Built 1997 Load: 49.9 t ADT: 271

WYO 257

Over: Unnamed Draw

Casper Streets, Natrona, WY

Built 2013 Load: 51.5 t ADT: 1,066

WYO 220

Over: North Platte River

13 Mi Sw Of Casper, Natrona, WY

Built 2002 Load: 53.9 t ADT: 3,066

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