County profile · official public datasets

Miami County, KS

326 public highway bridges tracked in the FHWA National Bridge Inventory: 64.7% rated Good, 31.9% Fair, 3.4% Poor.

326
Public bridges: 64.7%
Good condition: 3.4%
Poor condition

The verdict

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

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

Top 41%
lowest Poor share in state: 3.4%
Poor-condition share: 326
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.

Miami County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Miami County ranks #43 of 104 Kansas counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.4%). Miami County, Kansas contains 326 public highway bridges. Roughly 64.7% are rated “Good,” 31.9% “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

326

Public highway bridges in Miami County

Good condition

64.7%

211 of 326 rated 7-9

Fair condition

31.9%

104 of 326 rated 5-6

Poor condition

3.4%

11 of 326 rated 4 or below

In-state Poor-share rank

#43 of 104

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

Condition distribution

Share of 326 NBI-tracked bridges by lowest applicable component rating.

Good

64.7% (211)

Fair

31.9% (104)

Poor

3.4% (11)

Miami County's Poor-condition bridges carry 1,161 vehicle crossings a day

That is 0.2% 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 106 crossings a day against 2,084 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 326 of 326 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

41.4% of Miami County's bridges have passed the 50-year mark

135 of the 326 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 64.7% 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 56.4% of the county's Poor-condition bridge traffic

Woodland Road over TRIB. TO SWEETWATER CRK, built 2005, carries 655 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 11-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,161 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

15
1920s

16
1930s

41
1940s

7
1950s

11
1960s

26
1970s

56
1980s

33
1990s

29
2000s

63
2010s

24
2020s

4

What this shows Construction peaked in the 2000s, when 63 of the county's bridges still in the inventory were built, which is 19.3% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1974) matches the Kansas average (1972).

How Miami County compares with Kansas's closest counties by inventory size

The 5 Kansas counties nearest Miami 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 1974 against a peer-group mean of 1968 is 6 years newer.

Showing the 5 closest of 103 Kansas counties eligible for comparison.

Bridge inventory size and condition shares for Miami County and the 5 Kansas counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Washington County	335	54.9%	41.2%	3.9%	1975
Franklin County	332	55.1%	40.7%	4.2%	1972
Montgomery County	326	32.2%	62.3%	5.5%	1969
Miami County (this page)	326	64.7%	31.9%	3.4%	1974
Marion County	324	39.2%	51.2%	9.6%	1959
Cherokee County	317	42.6%	53%	4.4%	1967

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

Similar inventory size

Nearest county inventories outside KS (326 bridges here).

Merrimack County, NH · 326 bridges
Washington County, OR · 326 bridges
St. Clair County, MI · 327 bridges
Henry County, IL · 328 bridges

Similar average build year

Nearest mean year-built outside KS (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 326 Good 211 Fair 104 Poor 11

Good-condition bridges (211)

Sort:

Miami County Bridge Snapshot

Condition distribution

Miami County's Poor-condition bridges carry 1,161 vehicle crossings a day

41.4% of Miami County's bridges have passed the 50-year mark

One structure carries 56.4% of the county's Poor-condition bridge traffic

How Miami County compares with Kansas'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 (211)

Victory Road

US-169 HIGHWAY NB

Ridgeview Rd

US-169 HIGHWAY SB

Waverly Rd RS 346

Metcalf Rd

Jingo RD

RS1021

319th Street

Osawatomie Rd

231st Street

US69 HWY SB

US-169 HIGHWAY SB

Sunflower Rd

K7 HWY

Osawatomie Rd

Woodland Rd

383rd ST

LOCAL RD.

383rd ST

295th ST

US-169 HIGHWAY SB

LOCAL ROAD

US69 HIGHWAY SB

US 69 HIGHWAY SB

SWITZER RD

327th 264

US 169 HWY NB

Broadway St

335th Street

223RD ST.

Bethel Church Road

LOCAL ROAD

299th Street

US-169 HIGHWAY SB

Metcalf Rd

335th St.

Indianapolis Rd

US-169 HIGHWAY NB

US-169 HIGHWAY NB

CO. LN RD 215TH ST

US-169/K-7 HWY NB

Crescent Hill Road

US-169 HIGHWAY SB

391st Street

347TH ST

US-169 HIGHWAY SB

US-169 HIGHWAY NB

Indianapolis Road

351st ST

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