Between Republic and the Canada–US border, an estimated daily average of 1,600 motorists used this segment of SR 21, making this section the busiest. The daily average has declined since 2006 and 2007, when a daily average of 1,700 motorists utilized the segment. Northeast of Republic, the highway passes Curlew Lake, the  Curlew Lake State Park and the communities of Malo and Curlew.
Between Republic and the Canada–US border, an estimated daily average of 1,600 motorists used this segment of SR 21, making this section the busiest. The daily average has declined since 2006 and 2007, when a daily average of 1,700 motorists utilized the segment. Northeast of Republic, the highway passes Curlew Lake, the  Curlew Lake State Park and the communities of Malo and Curlew.