From Waiouru, the highway follows tributaries of the Rangitikei River through Taihape to meet the main river at Utiku. It then follows the western bank of the Rangitikei through Ohingaiti and Hunterville to Bulls. At Bulls, SH 1 turns southeast to cross the river, turning southwest again down the road at Sanson. SH 1 crosses the Manawatu Plain, passing the city of Palmerston North about west of it. It passes through Foxton, before reaching the end of the plain at Levin.