County profile · official public datasets

Boone County, IN

293 public highway bridges tracked in the FHWA National Bridge Inventory: 39.9% rated Good, 55.3% Fair, 4.8% Poor.

293
Public bridges: 39.9%
Good condition: 4.8%
Poor condition

The verdict

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

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

Top 50%
lowest Poor share in state: 4.8%
Poor-condition share: 293
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.

Boone County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Boone County ranks #46 of 92 Indiana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.8%). Boone County, Indiana contains 293 public highway bridges. Roughly 39.9% are rated “Good,” 55.3% “Fair,” and 4.8% “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

293

Public highway bridges in Boone County

Good condition

39.9%

117 of 293 rated 7-9

Fair condition

55.3%

162 of 293 rated 5-6

Poor condition

4.8%

14 of 293 rated 4 or below

In-state Poor-share rank

#46 of 92

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

Condition distribution

Share of 293 NBI-tracked bridges by lowest applicable component rating.

Good

39.9% (117)

Fair

55.3% (162)

Poor

4.8% (14)

Boone County's Poor-condition bridges carry 16,858 vehicle crossings a day

That is 1% of the county's reported daily bridge traffic on 4.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,204 crossings a day against 4,560 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 292 of 293 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

50.9% of Boone County's bridges have passed the 50-year mark

149 of the 293 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 39.9% 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 44.5% of the county's Poor-condition bridge traffic

SR 32 over FINLEY CREEK, built 1958, carries 7,502 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 14-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 16,858 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

2
1900s

3
1910s

4
1920s

15
1930s

23
1940s

15
1950s

13
1960s

51
1970s

28
1980s

33
1990s

34
2000s

30
2010s

20
2020s

22

What this shows Construction peaked in the 1960s, when 51 of the county's bridges still in the inventory were built, which is 17.4% 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 Boone County compares with Indiana's closest counties by inventory size

The 5 Indiana counties nearest Boone County in number of bridges, with their condition splits. Its 4.8% Poor share is the 4th-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1974 is in line with the group.

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

Bridge inventory size and condition shares for Boone County and the 5 Indiana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Madison County	301	44.5%	52.5%	3%	1978
Vigo County	296	44.9%	50.7%	4.4%	1977
Boone County (this page)	293	39.9%	55.3%	4.8%	1974
Knox County	290	40%	55.2%	4.8%	1976
Putnam County	290	30.3%	51%	18.6%	1963
Grant County	280	38.6%	59.6%	1.8%	1975

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

Similar inventory size

Nearest county inventories outside IN (293 bridges here).

Delaware County, IA · 293 bridges
Hocking County, OH · 293 bridges
Franklin County, PA · 294 bridges
Bedford County, TN · 294 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 293 Good 117 Fair 162 Poor 14

All bridges (293)

Sort:

Boone County Bridge Snapshot

Condition distribution

Boone County's Poor-condition bridges carry 16,858 vehicle crossings a day

50.9% of Boone County's bridges have passed the 50-year mark

One structure carries 44.5% of the county's Poor-condition bridge traffic

How Boone 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

All bridges (293)

CR 900E

CR 550S

PERRY-WORTH ROAD

INDIANAPOLIS AVE.

INDIANAPOLIS AVE.

N MERIDIAN STREET

E FORDICE STREET

CR 300S

CR 700 S

CR 800 S/CO LINE R

I-65 SB

CR 400N

CR 500W

246TH ST/CR 700 N

CR 300E

DEAD END AVENUE

I-465 NB

I-74 EB

I-74 WB

CR 450N

SR 47

I-465 NB TO I-865

206TH ST/CR 300 N

CR 450N

CR 1200E

SR 39

SR 75

US 421

CR 500E

CR 500W

SR 47

CR 450N

PATTERSON STREET

MOUNT ZION ROAD

CR 825N

CR 675N

I-65 NB

I-65 SB

E WASHINGTON ST.

CR 1050W

CR 300S

I-65 NB

I-865 EB

I-865 WB

CR 600E

I-65 NB

US 52 WB

CR 200S

WHITESTOWN PKWY

CR 550N

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