County profile · official public datasets

Boone County, MO

334 public highway bridges tracked in the FHWA National Bridge Inventory: 49.4% rated Good, 46.7% Fair, 3.9% Poor.

334
Public bridges: 49.4%
Good condition: 3.9%
Poor condition

The verdict

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

Boone County pairs a top-10% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 10%
lowest Poor share in state: 3.9%
Poor-condition share: 334
public highway bridges: 1984
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 #11 of 115 Missouri counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.9%). Boone County, Missouri contains 334 public highway bridges. Roughly 49.4% are rated “Good,” 46.7% “Fair,” and 3.9% “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

334

Public highway bridges in Boone County

Good condition

49.4%

165 of 334 rated 7-9

Fair condition

46.7%

156 of 334 rated 5-6

Poor condition

3.9%

13 of 334 rated 4 or below

In-state Poor-share rank

#11 of 115

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

Condition distribution

Share of 334 NBI-tracked bridges by lowest applicable component rating.

Good

49.4% (165)

Fair

46.7% (156)

Poor

3.9% (13)

Boone County's Poor-condition bridges carry 53,532 vehicle crossings a day

That is 3% of the county's reported daily bridge traffic on 3.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 4,118 crossings a day against 4,748 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 334 of 334 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

26.3% of Boone County's bridges have passed the 50-year mark

88 of the 334 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 49.4% 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 42.6% of the county's Poor-condition bridge traffic

IS 70 E over PERCHE CR, built 1958, carries 22,820 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 13-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 53,532 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

11
1930s

5
1940s

7
1950s

26
1960s

21
1970s

32
1980s

105
1990s

26
2000s

46
2010s

43
2020s

12

What this shows Construction peaked in the 1980s, when 105 of the county's bridges still in the inventory were built, which is 31.4% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1984, 5 years newer than the Missouri average of 1979.

How Boone County compares with Missouri's closest counties by inventory size

The 5 Missouri counties nearest Boone County in number of bridges, with their condition splits. Its 3.9% Poor share is the 1st-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1983 is in line with the group.

Showing the 5 closest of 114 Missouri counties eligible for comparison.

Bridge inventory size and condition shares for Boone County and the 5 Missouri counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Boone County (this page)	334	49.4%	46.7%	3.9%	1984
Franklin County	331	38.7%	56.8%	4.5%	1988
Harrison County	331	39.6%	39%	21.5%	1981
Bates County	319	22.6%	70.2%	7.2%	1977
Audrain County	314	41.4%	53.8%	4.8%	1987
Linn County	313	39%	43.5%	17.6%	1980

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 Missouri so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MO (334 bridges here).

Dodge County, NE · 334 bridges
Washoe County, NV · 334 bridges
Shelby County, IL · 335 bridges
Washington County, KS · 335 bridges

Similar average build year

Nearest mean year-built outside MO (1984 here).

Hennepin County, MN · avg 1984 · 936 bridges
Duval County, FL · avg 1984 · 831 bridges
El Paso County, CO · avg 1984 · 686 bridges
Bell County, TX · avg 1984 · 660 bridges

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

All 334 Good 165 Fair 156 Poor 13

Good-condition bridges (165)

Sort:

Boone County Bridge Snapshot

Condition distribution

Boone County's Poor-condition bridges carry 53,532 vehicle crossings a day

26.3% of Boone County's bridges have passed the 50-year mark

One structure carries 42.6% of the county's Poor-condition bridge traffic

How Boone County compares with Missouri'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 (165)

OLD RTE K

RT BB E

MO 163 S

BURR OAK RD

PROVIDENCE RD

RIVER RD

MEXICO GRAVEL RD

E ST CHARLES RD

US 63 S

RT OO E

US 63 S

ROLLING HILLS RD

IS 70 W

SCOTT BLVD

REMIE RD

MO 22 E

TIMMONS RD

DISCOVERY PKWY S

CHAPEL HILL RD

SCOTT BLVD

PATTON RD

IS 70 E

UNIVERSITY LANE

UNIVERSITY LANE

MO 124 E

MARSHALL LN

MO 124 E

US 63 N

NEW HAVEN ROAD

MO 763 S

ELLIS SCHOOL RD

RT WW E

RT Z S

IS 70 E

OR 70 E

OR 70 E

IS 70 W

IS 70 E

RANGELINE RD

IS 70 E

IS 70 E

RT UU W

IS 70 E

IS 70 W

MAGUIRE BLVD

PERCHE CHURCH RD

US 63 S

RT M E

MAUPIN LANE

RT F S

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