County profile · official public datasets

Dearborn County, IN

145 public highway bridges tracked in the FHWA National Bridge Inventory: 35.9% rated Good, 51.7% Fair, 12.4% Poor.

145
Public bridges: 35.9%
Good condition: 12.4%
Poor condition

The verdict

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

Dearborn County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

88th
of 92 on Poor share: 12.4%
Poor-condition share: 145
public highway bridges: 1974
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.

Dearborn County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Dearborn County ranks #88 of 92 Indiana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 12.4%). Dearborn County, Indiana contains 145 public highway bridges. Roughly 35.9% are rated “Good,” 51.7% “Fair,” and 12.4% “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

145

Public highway bridges in Dearborn County

Good condition

35.9%

52 of 145 rated 7-9

Fair condition

51.7%

75 of 145 rated 5-6

Poor condition

12.4%

18 of 145 rated 4 or below

In-state Poor-share rank

#88 of 92

Among Indiana counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 145 NBI-tracked bridges by lowest applicable component rating.

Good

35.9% (52)

Fair

51.7% (75)

Poor

12.4% (18)

Dearborn County's Poor-condition bridges carry 11,142 vehicle crossings a day

That is 1.8% of the county's reported daily bridge traffic on 12.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 619 crossings a day against 5,266 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 145 of 145 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

44.8% of Dearborn County's bridges have passed the 50-year mark

65 of the 145 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 35.9% 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 37.2% of the county's Poor-condition bridge traffic

SR 46 over WHITEWATER RIVER, built 1937, carries 4,142 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 18-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 11,142 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

3
1910s

4
1920s

4
1930s

15
1940s

8
1950s

6
1960s

21
1970s

12
1980s

21
1990s

19
2000s

8
2010s

15
2020s

9

What this shows Construction peaked in the 1960s, when 21 of the county's bridges still in the inventory were built, which is 14.5% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1974) matches the Indiana average (1978).

How Dearborn County compares with Indiana's closest counties by inventory size

The 5 Indiana counties nearest Dearborn County in number of bridges, with their condition splits. Its 12.4% Poor share is the 6th-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1979 is 5 years older.

Showing the 5 closest of 91 Indiana counties eligible for comparison.

Bridge inventory size and condition shares for Dearborn County and the 5 Indiana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Benton County	151	45.7%	52.3%	2%	1986
Perry County	151	41.1%	57%	2%	1978
Owen County	150	38.7%	51.3%	10%	1978
DeKalb County	149	40.9%	59.1%	0%	1980
Floyd County	145	34.5%	60.7%	4.8%	1974
Dearborn County (this page)	145	35.9%	51.7%	12.4%	1974

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 Dearborn 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 Dearborn County, both outside Indiana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IN (145 bridges here).

McDonald County, MO · 145 bridges
Lenoir County, NC · 145 bridges
Washington County, RI · 145 bridges
Monroe County, TN · 145 bridges

Similar average build year

Nearest mean year-built outside IN (1974 here).

Knox County, TN · avg 1974 · 588 bridges
Summit County, OH · avg 1974 · 563 bridges
Onondaga County, NY · avg 1974 · 472 bridges
Orange County, NY · avg 1974 · 472 bridges

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

All 145 Good 52 Fair 75 Poor 18

Good-condition bridges (52)

Sort:

Dearborn County Bridge Snapshot

Condition distribution

Dearborn County's Poor-condition bridges carry 11,142 vehicle crossings a day

44.8% of Dearborn County's bridges have passed the 50-year mark

One structure carries 37.2% of the county's Poor-condition bridge traffic

How Dearborn County compares with Indiana's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (52)

CHESTERVILLE RD

WHITE PLAINS RD

COLLIER RIDGE RD

HOGAN HILL RD

N HOGAN ROAD

HOLT RD

US 50 EB

US 50 WB

W COUNTY LINE RD

HARRISN BRKVILL RD

SR 1

LOWER DILLSBORO RD

INDIANA AVENUE

COLD SPRING RD

N DEARBORN RD

WOLIUNG RD

PLATT RD

SR 62

TURKEY POINT RD

LAKE TAMBO RD

I-74 EB

SR 46

I-74 EB

I-74 WB

UNION RIDGE ROAD

SR 62

BLUE CREEK RD

SR 46

SCHWIPPS RD

SR 46

SR 46

I-275 NB

JAMISON RD

BISCHOFF HILL RD

KAISER DR

RED BRIDGE RD

I-74 RAMP

SANGAMAW RD

N HOGAN RD

SR 1

I-74 WB

I-74 EB

I-74 WB

WEISBURG RD

I-74 WB

I-74 EB

E LAUGHERY CR RD

SHORT RIDGE RD

INDIANA AVE

SR 48

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