Footage shows the final piece of the collapsed Baltimore bridge following a deadly collision with a cargo ship in March.

The Unified Command team overseeing the operation removed the metal girders from the bottom of the Patapsco River on June 4.

Engineers are seen in the video lifting and removing the 420-short-tonne segment, known as 'Section 4C' from the riverbed.

The intricate operation began with hours of pounding using a concrete breaker on the first day, followed by precise cuts with blow torches on the second.

Salvors successfully separated several tonnes of concrete roadway and rebar from Section 4C, which had been blocking approximately 40 per cent of the 700ft wide by 50ft deep Fort McHenry Federal Channel.

Salvage work continues as barges and clamshell dredge grabs remove additional residual wreckage to be transported to Sparrows Point, Maryland, for processing.

The Francis Scott Key Bridge was destroyed when the Dali cargo vessel reportedly lost power before ramming into a support pillar, plunging the structure into the river as it fell apart within seconds early morning on March 26.

The ship's pilot reportedly issued a 'mayday call' minutes before the collision, allowing Maryland transportation officers to stop oncoming traffic onto the bridge.