US Bridges

Mn 39 over ST Louis River

FairPosted for load

St. Louis County, Minnesota · 0.9 MI E of JCT TH 23 · Structure no. 6544

Built
1910
115 years old, rebuilt 1970
Condition
Fair
inspected August 2024
Type
Movable - Swing
Steel
Length
1,889 ft
2 main spans
Daily traffic
3,474
2022 count
Owner
Railroad
Railroad

About this bridge

Mn 39 over ST Louis River is a steel movable - swing carrying Mn 39 over ST Louis River in St. Louis County, Minnesota. It was built in 1910 and reconstructed in 1970, so it is 115 years old, older than the Minnesota average of 38.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 3,474 vehicles a day, roughly 18% of them trucks, projected to reach 2,700 by 2042. The structure is 1,889 ft (575.7 m) long and 25 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

Open in Google Maps
CarriesMn 39
CrossesST Louis River
Location0.9 MI E of JCT TH 23
RouteState Highway 39
CountySt. Louis County
StateMinnesota
Coordinates46.65673, -92.20166
Functional classUrban Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2024
Inspection intervalevery 12 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating59.4 US tons
Inventory rating36 US tons

Structure

Structure typeMovable - Swing
MaterialSteel
DeckConcrete, cast-in-place
Main spans2 (+32 approach)
Design loadHS 20
Structure length1,889 ft (575.7 m)
Longest span150 ft (45.7 m)
Deck width25 ft (7.6 m)
Roadway width23 ft (6.9 m)
Vertical clearance over deck14 ft (4.3 m)

Traffic and service

Average daily traffic3,474 (2022)
Projected traffic2,700 by 2042
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and railroad
CrossesWaterway
Detour if closed11.8 mi (19 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerRailroad
Maintained byRailroad
Historic statusEligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost$1,000 million
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was Mn 39 over ST Louis River built?

It was built in 1910, making it 115 years old in 2025. It was reconstructed in 1970.

What condition is Mn 39 over ST Louis River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in August 2024.

How much traffic does Mn 39 over ST Louis River carry?

About 3,474 vehicles per day (2022 count), of which roughly 18% are trucks.

How long is Mn 39 over ST Louis River?

The structure is 1,889 ft (575.7 m) long with a longest span of 150 ft (45.7 m) and a deck 25 ft wide.

Who owns Mn 39 over ST Louis River?

It is owned by the Railroad.