County profile · official public datasets

St. Charles County, MO

417 public highway bridges tracked in the FHWA National Bridge Inventory: 32.4% rated Good, 64.3% Fair, 3.4% Poor.

417
Public bridges: 32.4%
Good condition: 3.4%
Poor condition

The verdict

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

St. Charles County pairs a top-5% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 5%
lowest Poor share in state: 3.4%
Poor-condition share: 417
public highway bridges: 1994
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.

St. Charles County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, St. Charles County ranks #6 of 115 Missouri counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.4%). St. Charles County, Missouri contains 417 public highway bridges. Roughly 32.4% are rated “Good,” 64.3% “Fair,” and 3.4% “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

417

Public highway bridges in St. Charles County

Good condition

32.4%

135 of 417 rated 7-9

Fair condition

64.3%

268 of 417 rated 5-6

Poor condition

3.4%

14 of 417 rated 4 or below

In-state Poor-share rank

#6 of 115

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

Condition distribution

Share of 417 NBI-tracked bridges by lowest applicable component rating.

Good

32.4% (135)

Fair

64.3% (268)

Poor

3.4% (14)

St. Charles County's Poor-condition bridges carry 60,988 vehicle crossings a day

That is 1.1% of the county's reported daily bridge traffic on 3.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 4,356 crossings a day against 11,038 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 417 of 417 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

14.9% of St. Charles County's bridges have passed the 50-year mark

62 of the 417 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 32.4% 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 64.2% of the county's Poor-condition bridge traffic

IS 64 W over IS 70, built 1971, carries 39,184 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 60,988 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

5
1930s

7
1940s

6
1950s

13
1960s

18
1970s

21
1980s

39
1990s

103
2000s

119
2010s

75
2020s

11

What this shows Construction peaked in the 2000s, when 119 of the county's bridges still in the inventory were built, which is 28.5% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1994, 15 years newer than the Missouri average of 1979.

How St. Charles County compares with Missouri's closest counties by inventory size

The 5 Missouri counties nearest St. Charles County in number of bridges, with their condition splits. Its 3.4% Poor share is the 1st-lowest of these 6. Its average build year of 1994 against a peer-group mean of 1983 is 11 years newer.

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

Bridge inventory size and condition shares for St. Charles County and the 5 Missouri counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Clay County	436	38.1%	55%	6.9%	1979
Stoddard County	434	43.1%	53.2%	3.7%	1976
St. Charles County (this page)	417	32.4%	64.3%	3.4%	1994
Jefferson County	411	33.6%	63%	3.4%	1981
Vernon County	401	35.4%	60.3%	4.2%	1988
Nodaway County	396	48%	37.6%	14.4%	1992

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 St. Charles 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 St. Charles County, both outside Missouri so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MO (417 bridges here).

Macomb County, MI · 417 bridges
Bedford County, PA · 417 bridges
Santa Barbara County, CA · 418 bridges
Lucas County, OH · 418 bridges

Similar average build year

Nearest mean year-built outside MO (1994 here).

Denton County, TX · avg 1994 · 991 bridges
Rock County, WI · avg 1994 · 304 bridges
Pitt County, NC · avg 1994 · 228 bridges
Columbus County, NC · avg 1994 · 226 bridges

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

All 417 Good 135 Fair 268 Poor 14

Fair-condition bridges (268)

Sort:

St. Charles County Bridge Snapshot

Condition distribution

St. Charles County's Poor-condition bridges carry 60,988 vehicle crossings a day

14.9% of St. Charles County's bridges have passed the 50-year mark

One structure carries 64.2% of the county's Poor-condition bridge traffic

How St. Charles 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

Fair-condition bridges (268)

BRYAN RD

CIVIC PARK DR

MEXICO RD

MEXICO RD

RP IS64E TO IS70E

POINT PRAIRIE RD

LITTLE HILLS EXPY

DEFIANCE RD

MEXICO RD

US 61 S

WENTZVILLE PKWY

MUEGGE RD

MUEGGE RD

MUEGGE RD

OLD DOMINION ST

KEYSTONE CROSSING

WINGHAVEN BLVD

PHOENIX PKWY

PEDROTTI LN

ELM POINT IND DR

PERRY CATE BLVD

WATERBURY FALLS

SUEMANDY DR

SUEMANDY DR

EXEC CENTRE PKWY

UPPER BOTTOM RD

DINGELDINE RD

KISKER RD

LAKE ST LOUIS BLVD

EAGLES HILL RIDG

OLD MORAY

ARENA PKWY

JUNGS STATION RD

PITMAN HILL RD

BATES RD

MO 79 S

GUTHRIE RD

STONE BEND TRAIL

VILLAGE CENTER DR

FALLON PKWY

AVONDALE SPRING DR

PIEPER RD

DEERFIELD ESTATE

KOCH RD

HENNING RD

GUTERMUTH RD

SUMMIT ESTATES DR

FIRST EXECUTIVE AV

BOONE HILLS DR

US 67 S

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