U.S. President Joe Biden Wednesday used part of the last day of his diplomatic visit to sub-Saharan Africa to tout the Lobito Corridor, a railway project backed by Washington that will link Angola’s port city of Lobito to the Democratic Republic of Congo and Zambia.

Biden toured the railway project alongside Angola’s President João Lourenço, DRC’s President Felix Tshisekedi and Zambia’s President Hakainde Hichilema.

White House officials say a second phase of the project envisions the extension of the Lobito Corridor through Tanzania.

The U.S. has provided a $550 million loan to support the venture, which involves refurbishing an existing railway through Angola and extending it into the DRC’s mining heartland as part of the first phase. No date has yet been given for its completion.