County profile · official public datasets

Marion County, SC

112 public highway bridges tracked in the FHWA National Bridge Inventory: 34.8% rated Good, 60.7% Fair, 4.5% Poor.

112
Public bridges: 34.8%
Good condition: 4.5%
Poor condition

The verdict

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

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

Top 39%
lowest Poor share in state: 4.5%
Poor-condition share: 112
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.

Marion County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Marion County ranks #18 of 46 South Carolina counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.5%). Marion County, South Carolina contains 112 public highway bridges. Roughly 34.8% are rated “Good,” 60.7% “Fair,” and 4.5% “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

112

Public highway bridges in Marion County

Good condition

34.8%

39 of 112 rated 7-9

Fair condition

60.7%

68 of 112 rated 5-6

Poor condition

4.5%

5 of 112 rated 4 or below

In-state Poor-share rank

#18 of 46

Among South Carolina counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 112 NBI-tracked bridges by lowest applicable component rating.

Good

34.8% (39)

Fair

60.7% (68)

Poor

4.5% (5)

Marion County's Poor-condition bridges carry 23,950 vehicle crossings a day

That is 5.6% of the county's reported daily bridge traffic on 4.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 4,790 crossings a day against 3,010 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 112 of 112 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

54.5% of Marion County's bridges have passed the 50-year mark

61 of the 112 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 34.8% 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 47.2% of the county's Poor-condition bridge traffic

SC 576 over CATFISH CANAL, built 1971, carries 11,300 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 5-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 23,950 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

3
1930s

11
1940s

7
1950s

6
1960s

17
1970s

25
1980s

13
1990s

10
2000s

7
2010s

13

What this shows Construction peaked in the 1970s, when 25 of the county's bridges still in the inventory were built, which is 22.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1974) matches the South Carolina average (1977).

How Marion County compares with South Carolina's closest counties by inventory size

The 5 South Carolina counties nearest Marion County in number of bridges, with their condition splits. Its 4.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1973 is in line with the group.

Showing the 5 closest of 45 South Carolina counties eligible for comparison.

Bridge inventory size and condition shares for Marion County and the 5 South Carolina counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Dillon County	128	25%	70.3%	4.7%	1972
Saluda County	125	40.8%	52.8%	6.4%	1973
Edgefield County	124	34.7%	62.9%	2.4%	1972
Georgetown County	113	33.6%	61.1%	5.3%	1977
Hampton County	113	25.7%	68.1%	6.2%	1972
Marion County (this page)	112	34.8%	60.7%	4.5%	1974

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 Marion 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 Marion County, both outside South Carolina so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside SC (112 bridges here).

Columbia County, FL · 112 bridges
Sumter County, FL · 112 bridges
Houston County, GA · 112 bridges
Tift County, GA · 112 bridges

Similar average build year

Nearest mean year-built outside SC (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 112 Good 39 Fair 68 Poor 5

All bridges (112)

Sort:

Marion County Bridge Snapshot

Condition distribution

Marion County's Poor-condition bridges carry 23,950 vehicle crossings a day

54.5% of Marion County's bridges have passed the 50-year mark

One structure carries 47.2% of the county's Poor-condition bridge traffic

How Marion County compares with South Carolina's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (112)

US 76

S-34-41

S-34-29

S-34-506

S-34-319

S-34-321

S-34-482

S-34-38

S-34-600

S-34-413

S-34-543

S-34-40

S-34-302

S-34-500

S-34-319

S-34-307

S-34-309

S-34-320

S-34-389

S-34-299

S-34-87

US 501

SC 41

SC 917

SC 41

US 301

S-34-19

S-34-744

US 76

S-34-692

SC 41

US 76 EB

S-34-34

S-34-34

S-34-540

S-34-680

S-34-34

S-34-86

S-34-757

S-34-774

SC 41

US 76 WB

US 501

US 501 SB

US 501 NB

US 378

US 501 BUS NBL

US 76

US 501 SB

US 501 SB

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