County profile · official public datasets

St. Mary's County, MD

50 public highway bridges tracked in the FHWA National Bridge Inventory: 26% rated Good, 70% Fair, 4% Poor.

50
Public bridges
26%
Good condition
4%
Poor condition

The verdict

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

St. Mary's County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 38%
lowest Poor share in state
4%
Poor-condition share
50
public highway bridges
1968
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.

St. Mary's County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, St. Mary's County ranks #9 of 24 Maryland counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4%). St. Mary's County, Maryland contains 50 public highway bridges. Roughly 26% are rated “Good,” 70% “Fair,” and 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

50

Public highway bridges in St. Mary's County

Good condition

26%

13 of 50 rated 7-9

Fair condition

70%

35 of 50 rated 5-6

Poor condition

4%

2 of 50 rated 4 or below

In-state Poor-share rank

#9 of 24

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

Condition distribution

Share of 50 NBI-tracked bridges by lowest applicable component rating.

Good
26% (13)
Fair
70% (35)
Poor
4% (2)

St. Mary's County's Poor-condition bridges carry 8,160 vehicle crossings a day

That is 2.4% of the county's reported daily bridge traffic on 4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 4,080 crossings a day against 5,002 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 50 of 50 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

60% of St. Mary's County's bridges have passed the 50-year mark

30 of the 50 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 26% 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 98.2% of the county's Poor-condition bridge traffic

MD 5 over HILTON RUN, built 1936, carries 8,010 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 8,160 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When St. Mary's County's bridges were built

50 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1950s, when 11 of the county's bridges still in the inventory were built, which is 22% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1968) matches the Maryland average (1972).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How St. Mary's County compares with Maryland's closest counties by inventory size

The 5 Maryland counties nearest St. Mary's County in number of bridges, with their condition splits. Its 4% Poor share is the 3rd-lowest of these 6. Its average build year of 1968 against a peer-group mean of 1973 is 5 years older.

Showing the 5 closest of 23 Maryland counties eligible for comparison.

Bridge inventory size and condition shares for St. Mary's County and the 5 Maryland counties closest to it in inventory size
County Bridges Poor
St. Mary's County (this page) 50 4%
Dorchester County 47 10.6%
Somerset County 46 6.5%
Kent County 44 4.5%
Talbot County 42 2.4%
Calvert County 33 0%

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 St. Mary's 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 St. Mary's County, both outside Maryland so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MD (50 bridges here).

Similar average build year

Nearest mean year-built outside MD (1968 here).

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

All 50 Good 13 Fair 35 Poor 2

All bridges (50)

CEDAR POINT RD

Fair

Over: HARPERS CREEK

0.7 MI N OF BRONSON RD, St. Mary's, MD

Built 1952 Load: 20.9 t ADT: 1,440

CEDAR POINT RD

Fair

Over: GOOSE CREEK

0.9 MI NE OF MACAULAY AVE, St. Mary's, MD

Built 1952 Load: 20.9 t ADT: 1,440

MD 5

Fair

Over: MOLL DYERS RUN

1.26 MILES S OF MD 244, St. Mary's, MD

Built 1937 Load: 27.7 t ADT: 12,500

MD 249

Fair

Over: ST GEORGES CREEK

0.46 MILE S OF STARK DR, St. Mary's, MD

Built 1957 Load: 28.1 t ADT: 1,530

MD 242

Fair

Over: TOMAKOKIN CREEK

0.71 MILE NORTH OF MD 238, St. Mary's, MD

Built 1936 Load: 29.9 t ADT: 5,491

MD 5

Fair

Over: MCINTOSH RUN

0.14 MILE SOUTH OF MD 243, St. Mary's, MD

Built 1935 Load: 31.3 t ADT: 22,220

MD 238

Fair

Over: NELSONS RUN

0.28 MILE SOUTH OF MD 234, St. Mary's, MD

Built 1929 Load: 32.7 t ADT: 1,791

MD 234

Fair

Over: NELSON RUN

0.43 MILE WEST OF MD 5, St. Mary's, MD

Built 1950 Load: 32.7 t ADT: 9,701

MD 242

Fair

Over: BR OF ST CLEMENTS CREEK

0.58 MILE SOUTH OF MD 5, St. Mary's, MD

Built 1951 Load: 33.1 t ADT: 2,431

MD 5

Fair

Over: ST MARYS RIVER

0.10 MILE NORTH OF MD 246, St. Mary's, MD

Built 1955 Load: 33.6 t ADT: 22,642

MD 5

Fair

Over: GLEBE RUN

0.11 MILE SOUTH OF MD 4, St. Mary's, MD

Built 1955 Load: 34.5 t ADT: 12,500

MD 5

Fair

Over: CHURCH CREEK

2.4 MILES SOUTH OF MD 584, St. Mary's, MD

Built 1936 Load: 34.5 t ADT: 4,400

MD 5

Fair

Over: FISHERMAN CREEK

0.31 MILE NORTH OF MD 584, St. Mary's, MD

Built 1936 Load: 35.4 t ADT: 7,244

MD 245

Fair

Over: BROOKS RUN

1.71 MILES S OF MD 235, St. Mary's, MD

Built 1950 Load: 35.4 t ADT: 8,324

PEGG ROAD

Fair

Over: BRANCH JARBOESVILLE RUN

.8 MI CHANCELLORS RUN RD, St. Mary's, MD

Built 1990 Load: 38.1 t ADT: 9,574

MD 471

Fair

Over: ST MARYS RIVER

0.36 MILE NORTH OF MD 5, St. Mary's, MD

Built 1932 Load: 39.0 t ADT: 4,242

DELABROOKE ROAD

Fair

Over: HORSE LANDING CREEK

2 MI E OF MD RTE 6, St. Mary's, MD

Built 1971 Load: 39.0 t ADT: 200

MD 234

Fair

Over: CHAPTICO CREEK

0.22 MILE WEST OF MD 238, St. Mary's, MD

Built 1959 Load: 39.5 t ADT: 8,121

MD 4

Fair

Over: KINGSTON CREEK

2.07 MILES N OF MD 235, St. Mary's, MD

Built 1980 Load: 43.1 t ADT: 26,801

MD 6

Fair

Over: LOCKS SWAMP CREEK

0.1 M W OF LAUREL VIEW LN, St. Mary's, MD

Built 1930 Load: 44.0 t ADT: 1,951

FENWICK STREET

Fair

Over: TOWN RUN

0.3 MILE NORTH OF MD 5, St. Mary's, MD

Built 1955 Load: 49.0 t ADT: 7,918

MD 244

Fair

Over: POPLAR HILL CREEK

0.16 M W OF TOWER HILL RD, St. Mary's, MD

Built 1938 Load: 53.5 t ADT: 2,517

MD 237

Fair

Over: JARBOESVILLE RUN

0.53 MILE NORTH OF MD 246, St. Mary's, MD

Built 2009 Load: 53.5 t ADT: 17,352

MD 238

Fair

Over: BURROUGHS RUN

1.49 MILES W OF MD 234, St. Mary's, MD

Built 1929 Load: 60.8 t ADT: 1,791

PEGG ROAD

Fair

Over: BRANCH JARBOESVILLE RUN

0.9 MI SOUTHWEST RT.235, St. Mary's, MD

Built 1995 Load: 62.6 t ADT: 4,891

MD 242

Fair

Over: LOCUST RUN

1.62 MILES SOUTH OF MD 5, St. Mary's, MD

Built 1929 Load: 76.2 t ADT: 2,371

MD 5

Fair

Over: EASTERN BRANCH

1.47 MILES N OF MD 489, St. Mary's, MD

Built 2016 Load: 82.3 t ADT: 10,000

MD 5

Fair

Over: ST CLEMENTS CREEK

0.72 MILE SOUTH OF MD 238, St. Mary's, MD

Built 1929 Load: 89.3 t ADT: 6,450

MD 4

Fair

Over: ST MARYS RIVER

1.1 MILES SOUTH OF MD 235, St. Mary's, MD

Built 1974 Load: 99.9 t ADT: 18,051

MD 5

Fair

Over: TOWN RUN

0.36 MILE SOUTH OF MD 245, St. Mary's, MD

Built 1990 Load: 99.9 t ADT: 21,360

HURRY RD

Fair

Over: NELSONS RUN

0.2 MI S OF MD RTE 238, St. Mary's, MD

Built 2008 Load: 99.9 t ADT: 1,427

STONEY RUN DRIVE

Fair

Over: WAREHOUSE RUN

1 MI W OF FLAT IRON ROAD, St. Mary's, MD

Built 1995 Load: 99.9 t ADT: 478

WILDEWOOD PARKWAY

Fair

Over: UNNAMED STREAM

.9 MI W OF WILDEWOOD BLVD, St. Mary's, MD

Built 1995 Load: 99.9 t ADT: 5,900

GREENS CROSSING CO

Fair

Over: CRANEY CREEK

0.6 MI E. OF FLAT IRON RD, St. Mary's, MD

Built 2009 Load: 99.9 t ADT: 603

WILDEWOOD DR.

Fair

Over: UNNAMED TRIBUTARY

0.2 M S OF WILDEWOOD PKWY, St. Mary's, MD

Built 2010 Load: 99.9 t ADT: 1,024

DOCTOR JOHNSON ROA

Good

Over: ST. CLEMENTS CREEK

0.9 MI W OF MD RTE 242, St. Mary's, MD

Built 1975 Load: 26.3 t ADT: 880

MD 234

Good

Over: BUDDS CREEK

ON CHARLES CO LINE, St. Mary's, MD

Built 1960 Load: 32.7 t ADT: 6,221

MD 242

Good

Over: DYNARD RUN

0.86 MILE SOUTH OF MD 234, St. Mary's, MD

Built 1960 Load: 32.7 t ADT: 5,491

MD 471

Good

Over: ST. MARYS RIVER

1.01 MILES NORTH OF MD 5, St. Mary's, MD

Built 1990 Load: 32.7 t ADT: 4,242

MD 242

Good

Over: ST CLEMENTS CREEK

0.52 MILE NORTH OF MD 234, St. Mary's, MD

Built 2000 Load: 36.7 t ADT: 2,371

MCINTOSH ROAD

Good

Over: MCINTOSH RUN

0.9 MI N OF MD RTE 245, St. Mary's, MD

Built 1984 Load: 43.5 t ADT: 2,500

MECHANICSVILLE RD

Good

Over: CHAPTICO CREEK

0.7 MI N OF MD RTE 234, St. Mary's, MD

Built 2011 Load: 44.4 t ADT: 2,876

MD 234

Good

Over: ST CLEMENTS CREEK

0.28 MILE EAST OF MD 242, St. Mary's, MD

Built 1950 Load: 54.9 t ADT: 9,701

MD 244

Good

Over: MOLL DYERS RUN

1.21 MILES WEST OF MD 5, St. Mary's, MD

Built 1925 Load: 63.0 t ADT: 2,190

BEN OAKS DRIVE

Good

Over: PERSIMMON CREEK

0.4 M NE OF MD 235, St. Mary's, MD

Built 2009 Load: 74.4 t ADT: 978

MD 470

Good

Over: TOMAKOKIN CREEK

0.88 MILE SOUTH OF MD 242, St. Mary's, MD

Built 1997 Load: 81.6 t ADT: 1,162

MD 6

Good

Over: PERSIMMON CREEK

2.44 MILES W OF MD 235, St. Mary's, MD

Built 2021 Load: 88.5 t ADT: 4,200

MD 5

Good

Over: BRANCH OF MCINTOSH RUN

.652 MILE SOUTH OF MD 243, St. Mary's, MD

Built 2017 Load: 99.9 t ADT: 22,220

CORNFIELD HARBOR D

Poor

Over: POINT LOOKOUT CREEK

1 Mile South of SR 5, St. Mary's, MD

Built 1970 Load: 15.0 t ADT: 150

MD 5

Poor

Over: HILTON RUN

1.86 MILES N OF MD 489, St. Mary's, MD

Built 1936 Load: 33.1 t ADT: 8,010

Read our methodology - how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.