Traffic Flow & Congestion
How is traffic volume and congestion evolving in San Joaquin County?
14,400 veh-hrs
Average daily vehicle hours of delay in 2023.
243
Traffic-proximity exposure index for San Joaquin County — 2020 observations, 2025 County Health Rankings release. The label is the release year, not the year traffic was observed.
198,550
Vehicle passages per average day across the Stanislaus County boundary’s six crossings in 2024 — the highest-volume county boundary.
Traffic Flow & Congestion
Traffic Congestion
Daily Vehicle Hours of Delay in San Joaquin County show major short-term surges in 2015–2016, followed by a period of stabilization through 2017–2019. A sharp decline in 2020 corresponds with reduced travel during the COVID-19 pandemic. Since 2021, the congestion levels have been steadily increasing, reflecting the region’s commuter flow patterns.
14,400 veh-hrs
Average daily vehicle hours of delay in 2023.
Traffic Volume
Traffic volume in California and in Merced, San Joaquin, and Stanislaus counties is measured as the average traffic volume per meter of major roadways, with greater weight given to traffic located closer to residential areas. The measure provides an indication of traffic-proximity exposure by considering both the volume of traffic and its proximity to residential populations. It is intended to describe the level of traffic exposure rather than demonstrate a trend in traffic patterns or changes over time.
The latest point represents 2020 observations, 2025 County Health Rankings release. Due to the observation year being 2020 and the release year is 2025, the latest point reflects the 2020 observation period rather than traffic conditions in 2025. The measure can be used to describe differences in traffic-proximity exposure across California and the three North San Joaquin Valley counties, but it does not by itself establish that traffic exposure caused a particular health outcome or that transportation infrastructure, travel behavior, or other interventions caused the reported values.
243
Traffic-proximity exposure index for San Joaquin County — 2020 observations, 2025 County Health Rankings release. The label is the release year, not the year traffic was observed.
Traffic Volumes at Gateways
In 2024, traffic across San Joaquin County’s 15 included state-highway crossings totalled an estimated 575,350 vehicle passages per average day. The Stanislaus County boundary had the highest combined volume at 198,550 across six crossings, followed by Alameda County at 178,100 across I-205 and I-580, and Sacramento County at 166,500 across three crossings. These figures include both travel directions and all vehicle types. They count passages rather than unique vehicles or people, so a vehicle crossing two gateways is counted at each.
Method: Ordinary crossings use one San Joaquin-side county-line AADT estimate, with documented neighboring-side exceptions. For I-580 from 2017 onward, separate directional observations approximately 0.03–0.05 mile inside the county boundary are combined; this change in source representation may affect comparisons over time. Route 26, the Calaveras boundary and the all-gateway total are unavailable for 2019–2020, and missing values do not mean zero traffic.
575,350
Estimated vehicle passages per average day across San Joaquin County’s 15 included state-highway crossings in 2024