The bridge came tumbling down early on Tuesday (local time) after a massive cargo freighter that had lost power ploughed into the structure in Baltimore Harbor. Two bodies have been recovered and four others are missing and presumed dead, believed to be trapped in a vehicle beneath concrete and steel that fell into the water.
Maryland Governor Wes Moore had requested the $60 million earlier on Friday, and within hours the US Department of Transportation's Federal Highway Administration approved the request to fund emergency work.
Such funding typically takes days, but President Joe Biden told reporters on Tuesday he had directed the federal government to "move heaven and earth" to quickly rebuild the bridge, which forms part of a highway looping around Baltimore.
Moore told a press conference the top priority was to recover the missing construction workers who were conducting repairs on the bridge when the vessel known as the Dali struck a support column about 1:30am.
Officials then hope to clear the channel in order to resume shipping operations; tend to workers, families and first responders affected by the tragedy; and rebuild the bridge.
But first a team of experts must assess how to remove the stuck vessel, loaded with thousands of containers and trapped by bridge debris. The US Army Corps of Engineers was bringing in the largest crane on the Eastern Seaboard to remove pieces of bridge, Moore said.
"The Dali is almost as long as the Eiffel Tower and the Dali has the Key Bridge on top of it. We're talking 3000 or 4000 tonnes of steel that's sitting on top of that ship," Moore said.
Until diving operations were suspended due to safety concerns on Wednesday night, divers searching for the victims had been impeded by the volume and density of the debris that blocked out sunlight.
"In most instances, our divers cannot see any more than a foot or two ahead of them, so much of the operation is simply feel," Moore said.
Federal officials have told Maryland lawmakers the final cost of rebuilding the bridge could soar to at least $US2 billion, Roll Call reported, citing a source familiar with the discussions.
The US Congress will need to fund building a replacement bridge.
Maryland officials said the emergency funds would support "mobilisation, operations, and debris removal, laying the foundation for a rapid recovery" and that the state may seek additional emergency funding as damage assessments progress.
Bound for Sri Lanka, the Singapore-flagged Dali reported losing power and the ability to manoeuvre before ploughing into a support pylon of the bridge.
The impact brought most of the bridge crashing into the mouth of the Patapsco River almost immediately, blocking shipping lanes and forcing the indefinite closure of the Port of Baltimore, one of the busiest on the US Eastern Seaboard.
