I-780  California (link)

6.50 miles [1]; from I-680 in Benicia to I-80 in Vallejo. It was approved as an interstate highway on Sept. 15, 1955, but as part of I-680. In July 1973, non-chargeable miles were added to California's system to allow 680 to be routed north along CA 21 toward Sacramento; the leftover portion of I-680 became Interstate 780. [2] Signing for this was updated around 1976.

See also: I-780 (Dan Faigin)

Sources

1. Route Log and Finder List - Interstate Highways, FHWA, Oct. 31, 2002.
2. 'History of California's Interstate Routes.' California Department of Transportation, November 1984.