The interchange with SR 189 at exit 4 both serves to funnel traffic so as to bypass around Nogales, Arizona, and Nogales, Sonora, for travelers bound to or from Hermosillo or Mexico City, and provides for the continuous flow of freight and truck traffic through the larger Mariposa Port of Entry to Highway 15, which has its northern terminus at the US–Mexico border with SR 189 and its southern terminus 2179 kilometers away in Mexico City.