State Route 128 is a 45-mile-long road in the state of Utah. The entire length of the highway has been designated the Upper Colorado River Scenic Byway, as part of the Utah Scenic Byways program.SR-128 begins just north of Moab, where it is commonly known as "the river road". The highway follows the southern bank of the Colorado River through a narrow, steep gorge.Between Moab and Castle Valley, the Colorado River, and indirectly, SR-128, form the southern boundary of Arches National Park.