County profile · official public datasets

Mercer County, ND

72 public highway bridges tracked in the FHWA National Bridge Inventory: 40.3% rated Good, 54.2% Fair, 5.6% Poor.

72
Public bridges: 40.3%
Good condition: 5.6%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Mercer County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 38%
lowest Poor share in state: 5.6%
Poor-condition share: 72
public highway bridges: 1975
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.

Mercer County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Mercer County ranks #20 of 53 North Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.6%). Mercer County, North Dakota contains 72 public highway bridges. Roughly 40.3% are rated “Good,” 54.2% “Fair,” and 5.6% “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.

Total bridges

Public highway bridges in Mercer County

Good condition

40.3%

29 of 72 rated 7-9

Fair condition

54.2%

39 of 72 rated 5-6

Poor condition

5.6%

4 of 72 rated 4 or below

In-state Poor-share rank

#20 of 53

Among North Dakota counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 72 NBI-tracked bridges by lowest applicable component rating.

Good

40.3% (29)

Fair

54.2% (39)

Poor

5.6% (4)

Mercer County's Poor-condition bridges carry 1,056 vehicle crossings a day

That is 3.1% of the county's reported daily bridge traffic on 5.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 264 crossings a day against 511 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 72 of 72 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

45.8% of Mercer County's bridges have passed the 50-year mark

33 of the 72 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 40.3% 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 73.9% of the county's Poor-condition bridge traffic

ND HIGHWAY 200 over BRANCH OF RAYMOND CREEK, built 1950, carries 780 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 4-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,056 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1930s

2
1940s

3
1950s

10
1960s

13
1970s

14
1980s

13
1990s

7
2000s

2
2010s

7

What this shows Construction peaked in the 1970s, when 14 of the county's bridges still in the inventory were built, which is 19.4% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1975) matches the North Dakota average (1975).

How Mercer County compares with North Dakota's closest counties by inventory size

The 5 North Dakota counties nearest Mercer County in number of bridges, with their condition splits. Its 5.6% Poor share is the 4th-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1978 is in line with the group.

Showing the 5 closest of 52 North Dakota counties eligible for comparison.

Bridge inventory size and condition shares for Mercer County and the 5 North Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Stutsman County	78	39.7%	53.8%	6.4%	1971
Dunn County	74	62.2%	35.1%	2.7%	1988
Mercer County (this page)	72	40.3%	54.2%	5.6%	1975
Bowman County	69	65.2%	31.9%	2.9%	1984
Emmons County	67	65.7%	31.3%	3%	1975
Cavalier County	66	24.2%	50%	25.8%	1973

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 Mercer 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 Mercer County, both outside North Dakota so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside ND (72 bridges here).

Lafayette County, AR · 72 bridges
Tattnall County, GA · 72 bridges
Wilkinson County, GA · 72 bridges
Kearny County, KS · 72 bridges

Similar average build year

Nearest mean year-built outside ND (1975 here).

San Bernardino County, CA · avg 1975 · 1,422 bridges
Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 72 Good 29 Fair 39 Poor 4

Fair-condition bridges (39)

Sort:

Mercer County Bridge Snapshot

Condition distribution

Mercer County's Poor-condition bridges carry 1,056 vehicle crossings a day

45.8% of Mercer County's bridges have passed the 50-year mark

One structure carries 73.9% of the county's Poor-condition bridge traffic

How Mercer County compares with North Dakota's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (39)

COUNTY HIGHWAY

COUNTY HIGHWAY

5TH ST SW

COUNTY HIGHWAY

55th Avenue SW

3rd Street SW

60TH AVE SW

County Road 37

72ND AVE SW

67th Ave SW

73rd Ave SW (CR2)

27TH ST. SW

9th Avenue NW

65TH AVE SW (CR25)

74th Ave SW

CR5 (73RD AVE SW)

67th Ave SW

County Highway 27

County Highway 27

69th Ave SW

3rd AVE

67 1/2 AVE SW

9th St. SW

ND HIGHWAY 200

71ST AVE SW/CR16

3rd St. SW

24TH ST SW (CR16)

County Highway 27

58TH AVE SW

ND HIGHWAY 200

ND HIGHWAY 200

ND HIGHWAY 200

63rd Ave SW

ND HIGHWAY 200

ND HIGHWAY 200

ND HIGHWAY 200

ND HIGHWAY 200

ND HIGHWAY 49

ND HIGHWAY 200

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