Construction on the original bridge was completed in 1968 and plans to replace it began 10 years ago.
Authorities say the Gerald Desmond Bridge carries about 15 percent of the nation's goods and is also a critical link for commuters. It serves as a connection between Long Beach and San Pedro, and between Orange County and western Los Angeles County.
The new one will be wider, higher and will sit just a few feet over from the current span. It will have three traffic lanes plus emergency lanes in both directions.
"The bridge is obsolete and deteriorating," said Port Executive Director Richard D. Steinke in a news release. "The new bridge will add lanes for improved traffic flow and dedicated safety lanes to keep traffic moving if there's a breakdown or accident."
The project will be funded by a local, state and federal money.