Total bridges
174
Public highway bridges in San Juan County
County profile · official public datasets
San Juan County, NM
174 public highway bridges tracked in the FHWA National Bridge Inventory: 36.8% rated Good, 56.9% Fair, 6.3% Poor.
- 174
- Public bridges
- 36.8%
- Good condition
- 6.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
San Juan County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 24th
- of 32 on Poor share
- 6.3%
- Poor-condition share
- 174
- public highway bridges
- 1977
- 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.
San Juan County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, San Juan County ranks #24 of 32 New Mexico counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). San Juan County, New Mexico contains 174 public highway bridges. Roughly 36.8% are rated “Good,” 56.9% “Fair,” and 6.3% “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.
Good condition
36.8%
64 of 174 rated 7-9
Fair condition
56.9%
99 of 174 rated 5-6
Poor condition
6.3%
11 of 174 rated 4 or below
In-state Poor-share rank
#24 of 32
Among New Mexico counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 174 NBI-tracked bridges by lowest applicable component rating.
Good 36.8% (64)
Fair 56.9% (99)
Poor 6.3% (11)
San Juan County's Poor-condition bridges carry 27,547 vehicle crossings a day
That is 2.7% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,504 crossings a day against 5,347 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 174 of 174 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
35.6% of San Juan County's bridges have passed the 50-year mark
62 of the 174 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 36.8% 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 59.6% of the county's Poor-condition bridge traffic
IRR/US64/491 WBL over SAN JUAN RIVER, built 1936, carries 16,419 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 11-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 27,547 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When San Juan County's bridges were built
174 bridges with a recorded construction year, grouped by decade
- 1920s 3
1920–1929
3 bridges
- 1930s 9
1930–1939
9 bridges
- 1940s 9
1940–1949
9 bridges
- 1950s 13
1950–1959
13 bridges
- 1960s
1960–1969
20 bridges
- 1970s
1970–1979
49 bridges
- 1980s
1980–1989
26 bridges
- 1990s 14
1990–1999
14 bridges
- 2000s 17
2000–2009
17 bridges
- 2010s 12
2010–2019
12 bridges
- 2020s 2
2020–2029
2 bridges
What this shows Construction peaked in the 1970s, when 49 of the county's bridges still in the inventory were built, which is 28.2% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1977) matches the New Mexico average (1973).
How San Juan County compares with New Mexico's closest counties by inventory size
The 5 New Mexico counties nearest San Juan County in number of bridges, with their condition splits. Its 6.3% Poor share is the 4th-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1971 is 6 years newer.
Showing the 5 closest of 31 New Mexico counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Socorro County | 188 | 16.5% | 76.1% | 7.4% | 1961 |
| Sandoval County | 182 | 40.7% | 54.4% | 4.9% | 1979 |
| San Miguel County | 175 | 41.1% | 50.9% | 8% | 1972 |
| San Juan County (this page) | 174 | 36.8% | 56.9% | 6.3% | 1977 |
| Rio Arriba County | 160 | 47.5% | 46.3% | 6.3% | 1973 |
| Colfax County | 140 | 37.9% | 57.1% | 5% | 1969 |
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 San Juan 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 San Juan County, both outside New Mexico so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside NM (174 bridges here).
- Hempstead County, AR · 174 bridges
- Eagle County, CO · 174 bridges
- Washington County, IN · 174 bridges
- Lac qui Parle County, MN · 174 bridges
Similar average build year
Nearest mean year-built outside NM (1977 here).
- San Diego County, CA · avg 1977 · 1,632 bridges
- King County, WA · avg 1977 · 1,238 bridges
- Riverside County, CA · avg 1977 · 1,117 bridges
- Shelby County, TN · avg 1977 · 1,077 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Good-condition bridges (64)
US-491 NBL
GoodOver: Captain Tom Wash
9.7 miles North of NM 134, San Juan, NM
Built 2012 Load: 36.6 t ADT: 5,862
45-Z001
GoodOver: STEVENS ARROYO
0.7 MI S US-64/FRUITLAND, San Juan, NM
Built 1975 Load: 37.1 t ADT: 1,620
IRR BIA RTE N5080
GoodOver: BRIMHALL WASH
BURNHAM CHAPTER HOUSE, San Juan, NM
Built 2003 Load: 38.5 t ADT: 110
US-64
GoodOver: UNNAMED WATERWAY
1.1 MI NE BROWNING PARKWA, San Juan, NM
Built 1940 Load: 38.9 t ADT: 19,182
IRR/US-491
GoodOver: UNNAMED WATERWAY
2.8 MI N OF NASCHITTI, San Juan, NM
Built 2013 Load: 39.2 t ADT: 5,746
NM-371
GoodOver: HUNTER WASH
34.2 MI S JCT 371 & P, San Juan, NM
Built 1984 Load: 39.4 t ADT: 2,500
RD 4280
GoodOver: unnamed wash
3.9 mi E-NE Navajo Dam, San Juan, NM
Built 2023 Load: 39.5 t ADT: 100
IRR/US-491 SB
GoodOver: TOCITO WASH
5.9 MI N ROAD TO TOADLENA, San Juan, NM
Built 1980 Load: 40.2 t ADT: 5,862
45-5500
GoodOver: SAN JUAN RIVER
0.80 MI S OF JCT US 64, San Juan, NM
Built 2022 Load: 41.0 t ADT: 3,063
NM-574
GoodOver: LA PLATA RIVER
0.3 MI E OF JCT NM 170, San Juan, NM
Built 2019 Load: 41.1 t ADT: 2,019
IRR/US-491-NBL
GoodOver: Pena Blanca Arroyo
1.86 M N Road to Toadlena, San Juan, NM
Built 2010 Load: 42.1 t ADT: 5,862
US-491 NB
GoodOver: Pena Blanca Wash
23.6 M S JCt 64/491, San Juan, NM
Built 2014 Load: 45.4 t ADT: 7,679
45-7150
GoodOver: GALLEGOS WASH
6.74 MI SW OF JCT US 550, San Juan, NM
Built 2015 Load: 46.0 t ADT: 642
US-491 NB
GoodOver: TOCITO WASH
5.9 MI N OF RD TO TOADLNA, San Juan, NM
Built 2005 Load: 63.5 t ADT: 5,862
Read our methodology - how this data is sourced, computed, and verified.
Related
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.