Interstate 205 California

Interstate 205 California


Interstate 205 is a short, well traveled freeway providing regional connectivity between the Central Valley of California and the San Francisco Bay Area. Running across the north side of Tracy, I-205 connects with I-5 north through Lathrop and SR 120 east to Manteca. West of Tracey at the Alameda County line, Interstate 205 links with I-580, the main route from the heart of the Central Valley into the Bay Area.

Although it bypasses Tracy, a growing bedroom community and transportation hub to south, Interstate 205 comprises a commuter route with six overall lanes. The freeway primarily channels traffic to the Bay Area via Interstate 580 and Altamont Pass from Stockton to the north, Manteca, Oakdale and Sonora to the east and Modesto, Turlock and Merced to the southeast.


Interstate 205 closely parallels old U.S. 50, which was decommissioned in 1964. U.S. 50 was upgraded to a freeway across Tracy during the early 1950s. Despite the highway predating the Interstate Highway System, Interstate 205 is considered an original 1956 Interstate Highway.1 Portions of the freeway along U.S. 50 were eventually incorporated into Business Loop I-205, which follows old U.S. 50 through Tracy along 11th Street.

Route Information

  • East End – Lathrop, CA

  • West End – Mountain House, CA

  • Mileage – 12.97

  • Cities – Tracy

  • JunctionsI-580 I-5

Source: December 31, 2021 Interstate Route Log and Finders List

I-205 Annual Average Daily Traffic (AADT)

Source: 2017 Traffic Volumes – Caltrans Traffic Census Program

The California Department of Public Works assigned 112 as the preliminary number of the future Interstate at Tracy as part of a route map submitted to the American Association of State Highway Officials (AASHO) on April 1, 1958. The route map utilized numbers in the first lower number block, avoiding 101 because of U.S. 101 and 104, 107, 108, 111 and 118 because those were existing state routes. Subsequent correspondence between AASHO and California on July 2 and 17, 1958 updated the route numbering plan, with 205 assigned to the route in Tracy because it connected I-5 with Interstate 5W. I-205 was approved as part of the statewide plan on November 10, 1958. Interstate 5W was eventually renumbered as part of I-580 in 1964.

Due to its role as a commuter route, the eastern end of Interstate 205 was widened from four to six lanes in 2007/08. I-205 expansion followed the four lane expansion of the freeway along SR 120 across Manteca, which accounted for the increase in traffic demands.

East End I-5 – Lathrop, California

I-205 East at I-5

I-205 east at I-5 - Lathrop, CA

Interstate 205 east defaults onto northbound I-5 at a wye interchange on the southern outskirts of Lathrop. 07/11/18

I-205 east at I-5 - Lathrop, CA

Interstate 205 adds three lanes to I-5 north ahead of the split with SR 120 east to Manteca. An end shield was previously posted at the bridge across Paradise Cut. 07/11/18

I-205 east at I-5 - 2003

The previous end shield for Interstate 205 at Paradise Cut. This assembly was removed with subsequent expansion of the freeway in 2007/08. 08/16/03

I-5 South at I-205

I-5 south at I-205 - Lathrop, CA

Traffic from the west end of SR 120 joins Interstate 5 south at the San Joaquin River in Lathrop. The freeway proceeds southwest with ten overall lanes to Exit 458 B for Interstate 205 west. 06/20/15

I-5 south at I-205 - Lathrop, CA

Representing the primary route to the East Bay and South Bay as well as the City of San Francisco, Interstate 205 is a crowded freeway across Tracy. 07/11/18

I-5 south at I-205 - Lathrop, CA

Exit 458 B parts ways with Interstate 5 (Westside Highway) southbound for I-205 west. The succeeding ramp (Exit 458 A) connects with Business Loop I-205 (Eleventh Street) along the historic route of U.S. 50 to Downtown Tracy. 07/11/18

Throwback – I-5 South at I-205

Former button copy signs for the separation of Interstate 205 west from I-5 (Westside Highway) south. 07/03/04

West End I-580 – Mountain House, California

I-580 East at I-205

I-580 east at I-205

Exit 63 departs Interstate 580 east for Grant Line Road and the Mountain House community just ahead of the separation with I-205 to Tracy. 07/11/18

I-580 east at I-205

The eight lane freeway partitions with I-580 branching southeast along a four lane freeway and I-205 extending east with six overall lanes. 07/11/18

I-580 east at I-205

Interstate 205 eastbound leads travelers to Modesto via SR 120 in addition to Stockton and Manteca. Since leaving Oakland, I-580 has followed the original route of the Lincoln Highway. I-205 overlays Historic U.S. 50 east to Tracy while I-580 converges with I-5 (Westside Highway) near Vernalis. 07/11/18

I-205 West at I-580

I-205 west at I-580

Interstate 205 westbound defaults onto I-580 at a wye interchange beyond the Edmund G. Pat Brown California Aqueduct. 06/20/15

I-205 west at I-580

Interstate 205 concludes just inside the Alameda County line and ahead of Altamont Pass. This is a major convergence area for the Golden State’s power grid. 06/20/15

I-580 West at I-205

I-580 west at I-205

Westbound Interstate 580 partitions into separate ramps at the wye interchange with I-205. The bypass ramp merges with the outside lanes ahead of the Exit 63 for Grant Line Road and the Mountain House community. 11/25/10

I-580 west at I-205

The I-580 mainline converges with I-205 with two lanes on the left side. 11/25/10

Throwback – I-580 East at I-205

Replaced button copy signs at the split of Interstate 205 east from I-580. 07/06/04


  1. California Celebrates 50 Years of the Interstate Highway System. Caltrans (California Department of Transportation).

Page updated July 3, 2022.