County profile · official public datasets

Northumberland County, PA

299 public highway bridges tracked in the FHWA National Bridge Inventory: 41.8% rated Good, 51.5% Fair, 6.7% Poor.

299
Public bridges: 41.8%
Good condition: 6.7%
Poor condition

The verdict

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

Northumberland County pairs a top-quartile lowest Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 13%
lowest Poor share in state: 6.7%
Poor-condition share: 299
public highway bridges: 1963
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.

Northumberland County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Northumberland County ranks #9 of 67 Pennsylvania counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.7%). Northumberland County, Pennsylvania contains 299 public highway bridges. Roughly 41.8% are rated “Good,” 51.5% “Fair,” and 6.7% “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

299

Public highway bridges in Northumberland County

Good condition

41.8%

125 of 299 rated 7-9

Fair condition

51.5%

154 of 299 rated 5-6

Poor condition

6.7%

20 of 299 rated 4 or below

In-state Poor-share rank

#9 of 67

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

Condition distribution

Share of 299 NBI-tracked bridges by lowest applicable component rating.

Good

41.8% (125)

Fair

51.5% (154)

Poor

6.7% (20)

Northumberland County's Poor-condition bridges carry 13,433 vehicle crossings a day

That is 1.5% of the county's reported daily bridge traffic on 6.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 746 crossings a day against 3,439 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 297 of 299 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

63.5% of Northumberland County's bridges have passed the 50-year mark

190 of the 299 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 41.8% 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 62.5% of the county's Poor-condition bridge traffic

W WALNUT ST over SHAMOKIN CREEK, built 1914, carries 8,400 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 20-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 13,433 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

12
1900s

12
1910s

11
1920s

15
1930s

35
1940s

23
1950s

21
1960s

25
1970s

39
1980s

25
1990s

29
2000s

19
2010s

29
2020s

4

What this shows Construction peaked in the 1970s, when 39 of the county's bridges still in the inventory were built, which is 13% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1963, 7 years older than the Pennsylvania average of 1970.

How Northumberland County compares with Pennsylvania's closest counties by inventory size

The 5 Pennsylvania counties nearest Northumberland County in number of bridges, with their condition splits. Its 6.7% Poor share is the 1st-lowest of these 6. Its average build year of 1963 against a peer-group mean of 1969 is 6 years older.

Showing the 5 closest of 66 Pennsylvania counties eligible for comparison.

Bridge inventory size and condition shares for Northumberland County and the 5 Pennsylvania counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Greene County	306	37.3%	46.7%	16%	1967
Indiana County	301	29.9%	51.2%	18.9%	1972
Beaver County	299	41.1%	48.8%	10%	1972
Northumberland County (this page)	299	41.8%	51.5%	6.7%	1963
Franklin County	294	29.6%	62.2%	8.2%	1964
Clearfield County	292	38.4%	47.6%	14%	1971

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

Similar inventory size

Nearest county inventories outside PA (299 bridges here).

Ada County, ID · 299 bridges
DeKalb County, AL · 300 bridges
Christian County, KY · 300 bridges
Washington County, MD · 300 bridges

Similar average build year

Nearest mean year-built outside PA (1963 here).

Worcester County, MA · avg 1963 · 1,014 bridges
Honolulu County, HI · avg 1963 · 682 bridges
Essex County, NJ · avg 1963 · 505 bridges
Passaic County, NJ · avg 1963 · 333 bridges

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

All 299 Good 125 Fair 154 Poor 20

Good-condition bridges (125)

Sort:

Northumberland County Bridge Snapshot

Condition distribution

Northumberland County's Poor-condition bridges carry 13,433 vehicle crossings a day

63.5% of Northumberland County's bridges have passed the 50-year mark

One structure carries 62.5% of the county's Poor-condition bridge traffic

How Northumberland County compares with Pennsylvania'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 (125)

SR 642

I-180 EBL

I-180 WBL

SR 44 @ ALLENWOOD

SR 61

I-180 EBL

T-456

SR 147

T-405 (Creek Road)

I-180 WBL

SR 1005

T-360 (Mandata Rd)

T-633 TURBOT TWP.

SR 0045

SR 0054

SR 147 SOUTHBOUND

SR 225

SR. 225

SR 405

SR 405

SR 487

SR 642

SR 901

SR 1010

S.R. 4002

SR 4002

SR 4006

SR 4022

SR 2001

N Mill Rd SR 1027

Boyles Run Rd

SR 1006

TWP RD. T722

SR 147

SR 2013

SR 2009 (T830)

SR 4020

I-180 EASTBOUND

I-80 WESTBOUND

I-80 EASTBOUND

SR 15

T-356 (DAUVA LUCH)

Roaring Creek Rd

I-180 WB

SR 642

SR 147

SR 147

SR 147 NB

SR 147 SB

SR 1007

Related