Interstate 580 provides the main link for regional traffic between the San Francisco Bay Area and Southern California along Interstate 5. Generally traveling east-west, Interstate 580 overlays several different roadways in the San Francisco Bay Area. The main sections of I-580 include:
- Richmond-San Rafael Bridge – the tolled northern crossing over the San Francisco and San Pablo Bay waterways
- John T. Knox Freeway – extending east from the Richmond-San Rafael Bridge and Point Richmond along industrial areas along the Richmond Inner Harbor to Interstate 80.
- Eastshore Freeway, – combines with Interstate 80 south from Albany to Berkeley and the Maze Interchange with I-880 and the San Francisco-Oakland Bay Bridge eastern approach in Oakland.
- MacArthur Freeway, – follows Historic U.S. 50 southeast from Oakland to Hayward.
- Arthur Breed Freeway, – continues along Historic U.S. 50 and goes east toward Dublin, Livermore, and the Central Valley, including the Altamont Pass and its windmills.
- William Elton Brown Freeway – branches southeast from Interstate 205 and bypasses Tracy along a rural, four lane stretch to Interstate 5.
Several sections of Interstate 580 were constructed prior to the Federal Highway Act of 1956, including the Livermore bypass and Altamont Pass freeway. Both segments opened as part of U.S. 50 prior to 1956.1 The Richmond-San Rafael Bridge over San Pablo Bay was completed in 1976 and designated California State Route 17.
When the Interstate Highway System was established, the I-580 corridor was incorporated in the longer Interstate 5W loop. I-5W was proposed to run northwest from near Tracy to Oakland, and then northeast along I-80 to Vacaville, where it would branch north to Dunnigan. The suffixed route was briefly posted along side Interstate 80 through Berkeley, but decommissioned in favor of I-505 and I-580 in 1964.
When it was designated, Interstate 580 consisted of the route west from the Central Valley to Livermore Valley and Dublin, through Dublin Canyon into Castro Valley, and north along the MacArthur Freeway to Oakland. A portion of this route west from I-205 overlaid old U.S. 50, and U.S. 48 before that.
This changed in 1984, when Interstate 580 was extended northwest as a result of California State Assembly Bill 2741. The legislation made a number of changes to the state highway system, including replacing State Route 17 west from Richmond to San Rafael as an extension of I-580, renumbering SR 17 (Nimitz Freeway) south from Oakland to San Jose as the new route for I-880, and creating both I-238 and I-980.