Interstate 205 California


Interstate 205 is a short, well-traveled freeway connecting the Central Valley of California with the San Francisco Bay Area. On its eastern end, it connects to Interstate 5 and California 120, a freeway that bypasses Manteca between Interstate 5 and California 99. On its western end, Interstate 205 connects to Interstate 580, which is the main route from the heart of the Central Valley into the Bay Area. Interstate 205 was likely given its number because it connected Interstate 5 and former Interstate 5W when first conceived. Interstate 5W is now part of Interstate 580.

Although it bypasses Tracy, a growing bedroom community and transportation hub to south, Interstate 205 primarily functions to channel traffic from the north (Stockton), east (Manteca, Oakdale, Sonora), and south (Modesto, Merced) to the Bay Area via Interstate 580 and the Altamont Pass. This disparity of control cities make the signage from side roads difficult. For instance, on Grant Line Road one sign shows Interstate 205 East Los Angeles and West San Francisco. The theory is that Interstate 205 east to California 120 east leads to California 99 to Los Angeles.

Due to its role as a commuter route, the four-lane configuration for Interstate 205 at the eastern end is inadequate and is planned for expansion to include more lanes. In addition, adjacent California 120 was recently widened from a Super Two to four lanes to account for its increase in traffic demands.

Historic U.S. Route and Business Loop

Interstate 205 closely parallels old U.S. 50, which was decommissioned in 1964. The original version of Interstate 205, which was constructed in the early 1950s, was signed as U.S. 50 and predates the Interstate Highway System. Even though the U.S. 50 freeway was already built before 1956, Interstate 205 is considered an original 1956 Interstate Highway.1 The old route, now known as Business Loop I-205, follows old U.S. 50 through Tracy via 11th Street. Business Loop I-205 is nearly as long as its parent, Interstate 205. The business loop begins on Interstate 205 just east of its junction with Interstate 580, and it ends on Interstate 5 just south of the Interstate 5/205 interchange. Signage for Business Loop I-205 is still present along southbound Interstate 5.

Highway Guides

Western Terminus - Interstate 580 - west of Tracy, California
Perspective from Interstate 580 east
Eastbound Interstate 580 approaching Grant Line Road, one mile. The next exit is Interstate 205; the eight-lane freeway will split into one four-lane and one six-lane freeway. Photo taken 08/22/03.
The first overhead sign for eastbound Interstate 205 appears at the Grant Line Road interchange. Interstate 580 is almost treated like an exit here, as Interstate 5 south is used as a destination for that road. Photo taken 08/22/03.
In addition to Stockton and Manteca, eastbound Interstate 205 also leads to Modesto. There are two ways to reach Modesto from here: Interstate 205 east to California 120 east to California 99 south or Interstate 580 east to California 132 east into Modesto. It is likely that the California 132 route is discouraged because it is a congested, two-lane highway between Interstate 580 and California 99, whereas the route via Interstate 205 is all freeway. Photo taken 08/22/03.
Traffic opting for eastbound Interstate 580 must remain in the right lanes; through traffic to eastbound Interstate 205 may use the left lanes. The tall power lines in the background of this picture are part of the major north-south power interconnection system serving California and the Pacific Northwest. Photo taken 08/22/03.
Eastbound Interstate 580 at Interstate 205. Since leaving Oakland, Interstate 580 has followed the original routing of the Lincoln Highway, U.S. 50. At this interchange, Interstate 580 will split away from that historic route and head along a comparably new alignment to meet the Westside Highway, Interstate 5. Meanwhile, Interstate 205 will continue east along the alignment of U.S. 50, with a business loop that follows the original road. Interstate 580 turns southeast at this interchange, headed toward Interstate 5 near Vernalis, while Interstate 205 follows a left exit toward Tracy and Stockton via Interstate 5. Photo taken 08/22/03.
This is the first reassurance shield along eastbound Interstate 580 after the exit for Interstate 205. Photo taken 08/22/03.
Perspective from Interstate 205 east
After the left exit, eastbound Interstate 205 begins its easterly journey by passing under the transition ramp carrying westbound Interstate 580 traffic. Photo taken 08/22/03.
The first exit along eastbound Interstate 205 after the Interstate 580 split is Exit 2, Mountain House Parkway. Photo taken 08/22/03.
Perspective from Interstate 205 west
Since there is no direct connection from westbound Interstate 205 to eastbound Interstate 580, one must use Exit 2, Mountain House Parkway south to Interstate 580. Note that this sign shows Interstate 580 as Los Angeles, the control city for Interstate 580 eastbound after splitting from Interstate 205. Photo taken 07/03/04.
Westbound Interstate 205 at Exit 2, Mountain House Parkway, the last exit before Interstate 580. In typical California style, no signs mention the end of Interstate 205 or the impending junction with Interstate 580. Photo taken 07/03/04.
Last westbound reassurance shield along Interstate 205 after the Mountain House Parkway on-ramp. Photo taken 08/22/03.
Interstate 205 enters Alameda County. Photo taken 07/03/04.
Large power line towers criss-cross the area around Tracy. This is a major convergence area for the Golden State's power grid. Photo taken 08/16/03.
Westbound Interstate 205 merges with westbound Interstate 580 traffic from the left after passing under the transition ramp. Photo taken 08/16/03.
Eastern Terminus - Interstate 5 - Tracy, California
Perspective from Interstate 5 south
Immediately after the California 120 interchange is the junction between Southbound Interstate 5 and westbound Interstate 205. This approach sign is one mile north of the interchange. Since Interstate 205 is the primary route to the East Bay and South Bay as well as the City of San Francisco, Interstate 205 is a very busy route. Photo taken 07/03/04.
Southbound Interstate 5 approaching Westbound Interstate 205, three-quarters of a mile. Photo taken 07/03/04.
Westbound Interstate 205 is signed primarily as serving San Francisco, but this auxiliary sign points to two other large cities in the Bay Area: Oakland (via Interstate 580) and San Jose (via Interstate 680). Photo taken 07/03/04.
Unlike most business routes in California, Business Loop I-205 receives two business loop notifications rather than just one. The first is this sign, which is one of many along southbound as Interstate 5 approaches Interstate 205. This kind of sign is unique to California, and it indicates that Interstate 205 freeway traffic should take the next exit, while business traffic should remain on Interstate 5 until the next exit. This signed was removed shortly after this photo was taken. Photo taken by Joel Windmiller (09/00).
Southbound Interstate 5 reaches the junction with Interstate 205 (to Interstate 580) and Business Loop I-205 through Tracy. Photo taken 07/03/04.
Perspective from Interstate 205 east
Last reassurance shield for Interstate 205 along eastbound after Exit 11. Photo taken 08/16/03.
After the last exit, Interstate 205 turns slightly northeast as it reaches toward Interstate 5. Photo taken 08/16/03.
As typical for California, there are no signs warning motorists that an Interstate is about to merge onto another Interstate. Therefore, there are no signs indicating the impending merge with Interstate 5 or the upcoming junction with California 120. Photo taken 08/16/03.
Interstate 205 passes over Interstate 5, the first indication that Interstate 205 is about to merge onto the other freeway. Photo taken 08/16/03.
Although there are no Interstate 5 merge warning signs, there is this end Interstate 205 shield assembly on the transition ramp from eastbound Interstate 205 to northbound Interstate 5. Photo taken 08/16/03.
After the end sign, the ramp passes into Lathrop, which an uncommonly graphical welcome sign. Photo taken 08/16/03.
Interstate 205 finally merges onto northbound Interstate 5. The signs in the distance are for California 120, which leads east to Manteca, Modesto, and Stockton. Photo taken 08/16/03.


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

Page Updated July 18, 2006.

Additional Info

State California
Mileage 12.97
Cities Tracy
Junctions I-580, I-5
Source: December 31, 2017 Interstate Route Log and Finders List
I-205 California Annual Average Daily Traffic

County Begin Milepost Location To: AADT
Alameda 0.21 I-580 San Joaquin County line (0.45) 106,000
San Joaquin 0.00 Alameda County line Patterson Pass Rd 110,000
San Joaquin 1.38 Patterson Pass Rd Old Route 50 119,000
San Joaquin 3.37 Old Route 50 Mac Arthur Dr 91,000
San Joaquin 8.13 Mac Arthur Dr I-5 (12.69) 92,000
Source: Caltrans, Traffic Operations Program - Traffic and Vehicle Data Systems [2002]