MO 21 S
Carrying MO 21 S over MATTESE CR
S 1988 T 44 N R 6 E, St. Louis, Missouri
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
MO 21 S in St. Louis, Missouri sits above 89% of rated Missouri bridges on inventory load rating (52 t), while its 1967 build year is earlier than 80% of St. Louis's recorded-year cohort (912 bridges).
MO 21 S in St. Louis, Missouri is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1967, it carries 1 rated component on the inspecting agency's 0-9 scale, and its weakest reported component scores 4. The lowest applicable rating sets the federal condition category, so this Poor result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure MO:956
INTERSTATE-ERA · CONCRETE · MULTI-SPAN · CULVERT-LED · HEAVY-ADT · HEAVY-LOAD · CAT-POOR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- CULVERT-LED Culvert-led
- HEAVY-ADT Heavy ADT
- HEAVY-LOAD Heavy load
- CAT-POOR Poor
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
Bridge Snapshot: MO 21 S
The MO 21 S bridge in St. Louis, Missouri carries MO 21 S over MATTESE CR. It was built in 1967, making it 59 years old today. The structure is built primarily of concrete continuous and spans 3 sections, stretching 9.7 meters (32 feet) end to end. Daily traffic averages 25,160 vehicles, placing it in the heavily-trafficked tier of Missouri bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show culvert at 4/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules.
How MO 21 S compares
Age against the county: built in 1967, earlier than 727 of St. Louis's 912 bridges with a recorded construction year (80%), against a county median build year of 1990. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Missouri bridges with a recorded inventory load rating (24,616 of 24,618 rated).
MO 21 S vs every rated Missouri bridge
Inventory load rating (metric tons), FHWA NBI, this state
52 Top 11% higher than 89% of 24,616 bridges
rated Missouri bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
St. Louis inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 912 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
Structural Details
- Year Built
- 1967
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 9.7 m (32 ft) 0
- Owner
- State Highway Agency
- Avg Daily Traffic
- 25,160 vehicles/day
- Structure Number
- 956
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
MO 21 S is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare MO 21 S against other structures in St. Louis and across Missouri. Missouri bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for MO 21 S?
MO 21 S in St. Louis, Missouri on the FHWA's 0–9 scale.
How often is MO 21 S inspected?
MO 21 S's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 25,160 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. MO 21 S is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for MO 21 S?
MO 21 S has an NBI inventory load rating of 52.2 metric tons.
Who is responsible for maintaining MO 21 S?
MO 21 S is owned and maintained by State Highway Agency.
How old is MO 21 S and does age affect safety?
MO 21 S was built in 1967, making it 59 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.