The route provides the most efficient and effective route for trucks to access around 50,000 hectares of production forest, said Ernst Zollner, NZTA regional director.
"Regional authorities and industry in Northland have been strongly advocating for this route to be classified as a State Highway because it accesses an area of significant economic activity both regionally and nationally," Mr Zollner said.
"The NZ Transport Agency acknowledges the growth potential of the forestry and wood processing industries in Northland and this decision shows our level of commitment to providing a package of investment and development across the region's roads."
NRC chairman Bill Shepherd said he is thrilled that Northland's collective call for an elevation in the route's status has found a receptive ear.
"While there are obviously some details still to be worked through, giving it State Highway status is key to our goal of a fit-for-purpose and resilient heavy transport route into the Far North in particular," Mr Shepherd said.
Whangarei District acting chief executive Simon Weston said that council was very pleased with the news.
"The information came in during Wednesday's council meeting at which we were discussing Mangakahia Road, so it was very timely," he said. "Our council is very keen to work with [other parties] to bring this change about. We look forward to us all forming a collaborative agreement for managing these roads."