County profile · official public datasets

Glenn County, CA

242 public highway bridges tracked in the FHWA National Bridge Inventory: 36.8% rated Good, 52.9% Fair, 10.3% Poor.

242
Public bridges: 36.8%
Good condition: 10.3%
Poor condition

The verdict

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

Glenn County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

46th
of 58 on Poor share: 10.3%
Poor-condition share: 242
public highway bridges: 1954
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.

Glenn County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Glenn County ranks #46 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10.3%). Glenn County, California contains 242 public highway bridges. Roughly 36.8% are rated “Good,” 52.9% “Fair,” and 10.3% “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

242

Public highway bridges in Glenn County

Good condition

36.8%

89 of 242 rated 7-9

Fair condition

52.9%

128 of 242 rated 5-6

Poor condition

10.3%

25 of 242 rated 4 or below

In-state Poor-share rank

#46 of 58

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

Condition distribution

Share of 242 NBI-tracked bridges by lowest applicable component rating.

Good

36.8% (89)

Fair

52.9% (128)

Poor

10.3% (25)

Glenn County's Poor-condition bridges carry 13,372 vehicle crossings a day

That is 2.7% of the county's reported daily bridge traffic on 10.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 535 crossings a day against 3,739 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 241 of 242 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

83.9% of Glenn County's bridges have passed the 50-year mark

203 of the 242 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 36.8% 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 31.1% of the county's Poor-condition bridge traffic

ROAD 99W over STONY CREEK, built 1913, carries 4,157 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 25-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 13,372 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

12
1920s

14
1930s

32
1940s

45
1950s

23
1960s

58
1970s

37
1980s

10
1990s

5
2000s

4
2010s

1

What this shows Construction peaked in the 1960s, when 58 of the county's bridges still in the inventory were built, which is 24% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1954, 16 years older than the California average of 1970.

How Glenn County compares with California's closest counties by inventory size

The 5 California counties nearest Glenn County in number of bridges, with their condition splits. Its 10.3% Poor share is the 5th-lowest of these 6. Its average build year of 1954 against a peer-group mean of 1968 is 14 years older.

Showing the 5 closest of 57 California counties eligible for comparison.

Bridge inventory size and condition shares for Glenn County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Yolo County	271	45.8%	49.4%	4.8%	1966
Madera County	247	34.8%	53.4%	11.7%	1973
Glenn County (this page)	242	36.8%	52.9%	10.3%	1954
Colusa County	211	40.8%	52.1%	7.1%	1968
Marin County	207	43.5%	46.9%	9.7%	1958
Trinity County	194	56.2%	39.7%	4.1%	1977

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

Similar inventory size

Nearest county inventories outside CA (242 bridges here).

Macoupin County, IL · 242 bridges
Wabaunsee County, KS · 242 bridges
Tuscola County, MI · 242 bridges
Kings County, NY · 242 bridges

Similar average build year

Nearest mean year-built outside CA (1954 here).

Graham County, AZ · avg 1954 · 179 bridges
Menard County, TX · avg 1954 · 63 bridges
Foard County, TX · avg 1954 · 60 bridges
Throckmorton County, TX · avg 1954 · 53 bridges

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

All 242 Good 89 Fair 128 Poor 25

Fair-condition bridges (128)

Sort:

Glenn County Bridge Snapshot

Condition distribution

Glenn County's Poor-condition bridges carry 13,372 vehicle crossings a day

83.9% of Glenn County's bridges have passed the 50-year mark

One structure carries 31.1% of the county's Poor-condition bridge traffic

How Glenn County compares with California'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 (128)

IRR BIA RTE 226

SOETH RD (RD 410)

COUNTY RD 50

ROAD 67

ROAD 67

ROAD 16

STATE ROUTE 162

ROAD 66B

ROAD 69

CO RD D

ROAD E

MONTGOMERY AVE

COUNTY ROAD 303

COUNTY RD P

ROAD 35

ROAD F

ROAD #60

ROAD 48

ROAD 34

COUNTY RD 306

CO RD #99 W

ROAD 99 W

COUNTY RD 306

ROAD 32

ROAD V

ROAD W

COUNTY ROAD 303

ROAD 67

CO ROAD C

COUNTY ROAD D

ROAD 61

COUNTY ROAD Z

ROAD Y

COUNTY RD 35

ROAD XX

COUNTY RD 306

CO RD 302 \ CLARKS

ROAD 48

ROAD 9

ROAD 60

ROAD 67

BAYLISS RD

COUNTY RD 29

COUNTY RD 24

CO RD #45

ROAD 45

ROAD 51

ROAD F

ROAD 48

COUNTY RD NO. 8

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