SAULT STE. MARIE, Mich. — President Donald Trump has signed a bill that’s a key step toward building a long-sought shipping lock on the waterway linking Lake Huron and Lake Superior.

Funding authorization for the Soo Locks project was included in a water resources bill that cleared the Senate this month.

The complex at Sault Ste. Marie has just one lock suitable for 1,000-foot freighters that haul iron ore and other cargo from Lake Superior along the St. Marys River to the other Great Lakes.

The bill allows construction of a second large lock , which the shipping industry and elected officials say is needed in case the older lock is disabled.

Congress still needs to appropriate funds in separate legislation over numerous years to pay for the $1 billion project.