County profile · official public datasets

Shasta County, CA

492 public highway bridges tracked in the FHWA National Bridge Inventory: 47.6% rated Good, 49.4% Fair, 3% Poor.

492
Public bridges: 47.6%
Good condition: 3%
Poor condition

The verdict

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

Shasta County posts a top-10% lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 7%
lowest Poor share in state: 3%
Poor-condition share: 492
public highway bridges: 1967
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.

Shasta County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Shasta County ranks #4 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3%). Shasta County, California contains 492 public highway bridges. Roughly 47.6% are rated “Good,” 49.4% “Fair,” and 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

492

Public highway bridges in Shasta County

Good condition

47.6%

234 of 492 rated 7-9

Fair condition

49.4%

243 of 492 rated 5-6

Poor condition

15 of 492 rated 4 or below

In-state Poor-share rank

#4 of 58

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

Condition distribution

Share of 492 NBI-tracked bridges by lowest applicable component rating.

Good

47.6% (234)

Fair

49.4% (243)

Poor

3% (15)

Shasta County's Poor-condition bridges carry 51,229 vehicle crossings a day

That is 1.8% of the county's reported daily bridge traffic on 3.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,415 crossings a day against 6,608 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 491 of 492 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

69.5% of Shasta County's bridges have passed the 50-year mark

342 of the 492 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 47.6% 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 35.1% of the county's Poor-condition bridge traffic

INTERSTATE 5 over CASTLE CREEK, built 1960, carries 18,000 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 15-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 51,229 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

8
1920s

19
1930s

38
1940s

39
1950s

55
1960s

134
1970s

74
1980s

39
1990s

32
2000s

29
2010s

17
2020s

8

What this shows Construction peaked in the 1960s, when 134 of the county's bridges still in the inventory were built, which is 27.2% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1967) matches the California average (1970).

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

The 5 California counties nearest Shasta County in number of bridges, with their condition splits. Its 3% Poor share is the 1st-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1965 is in line with the group.

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

Bridge inventory size and condition shares for Shasta County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Merced County	528	32.2%	59.5%	8.3%	1967
Ventura County	501	55.7%	40.1%	4.2%	1969
Shasta County (this page)	492	47.6%	49.4%	3%	1967
Tehama County	450	36.9%	56.2%	6.9%	1961
Imperial County	444	50.7%	40.5%	8.8%	1968
Butte County	437	31.8%	62%	6.2%	1958

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

Similar inventory size

Nearest county inventories outside CA (492 bridges here).

Lyon County, KS · 492 bridges
Greene County, MO · 493 bridges
Canadian County, OK · 493 bridges
Vermilion County, IL · 494 bridges

Similar average build year

Nearest mean year-built outside CA (1967 here).

Allegheny County, PA · avg 1967 · 1,294 bridges
Suffolk County, MA · avg 1967 · 489 bridges
Multnomah County, OR · avg 1967 · 473 bridges
Le Flore County, OK · avg 1967 · 469 bridges

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

All 492 Good 234 Fair 243 Poor 15

Good-condition bridges (234)

Sort:

Shasta County Bridge Snapshot

Condition distribution

Shasta County's Poor-condition bridges carry 51,229 vehicle crossings a day

69.5% of Shasta County's bridges have passed the 50-year mark

One structure carries 35.1% of the county's Poor-condition bridge traffic

How Shasta 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

Good-condition bridges (234)

HILLTOP DR

HARTNELL AVE

INTERSTATE 5 SB

INTERSTATE 5 NB

STATE ROUTE 44

STATE ROUTE 44

INTERSTATE 5

STATE ROUTE 44

STATE ROUTE 44

POLLARD FLAT ROAD

GIBSON ROAD

SLATE CREEK ROAD

INTERSTATE 5

MCCARDLE FLAT ROAD

VICTOR AVENUE

STATE ROUTE 44

INTERSTATE 5 NB

INTERSTATE 5 SB

INTERSTATE 5 NB

STATE ROUTE 299

STATE ROUTE 273

SR 89

STATE ROUTE 44

STATE ROUTE 36

INTERSTATE 5

INTERSTATE 5 SB

INTERSTATE ROUTE 5

INTERSTATE ROUTE 5

INTERSTATE 5

INTERSTATE 5

LOWER GAS POINT RD

IRON MOUNTAIN ROAD

BRIDGE ST

OLD 44 DRIVE

HARTNELL AVE

SOUTH ST

OASIS ROAD

BLACK BUTTE RD

VEDDER RD

BUZZARD ROOST ROAD

CLINE GULCH ROAD

WILCOX ROAD

NELSON CREEK RD

BRESLAUER LANE

IRON MT. RD

NORTH BONNYVIEW RD

OLD 44 DR

HIDDEN LANE

BERYL DR

ZOGG MINE RD

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