State Highway 6 follows virtually the complete length of the river. From near Haast Pass, the state highway is located on the river's true left. It switches to the true right at the Gates of Haast Bridge. At Pleasant Flat, where the valley widens out, the state highway crosses back to the true left. The final bridge is near the coast, just after the turnoff to the Haast township. At it is the longest one-lane road bridge in New Zealand, and the 7th longest New Zealand bridge overall.