The 2.2-mile span that cost $6.4 billion -- more than five times the amount projected -- opened Monday night with a chain-cutting ceremony featuring transportation officials, engineers, contractors and politicians, the Oakland (Calif.) Tribune reported.
Lt. Gov. Gavin Newsom cut the chain with a welding torch as Oakland Mayor Jean Quan and San Francisco Mayor Ed Lee looked on, the newspaper said.
People gathered for the chain-cutting ceremony were the first to cross the bridge in classic and newer electric cars in a parade-like procession, the Tribune reported.
The bridge was originally supposed to open 6 a.m. Tuesday for early rush-hour traffic, the Los Angeles Times reported.
The new bridge replaces the old Bay Bridge, damaged in the 1989 Loma Prieta earthquake, which shook loose a piece of the upper deck.