I researched this topic and there aren't .

DTW/SLC ties IAH/BOI as the longest regional jet route in North America (and probably the world). The former was flown with a CRJ-200, the latter with a long-range ERJ - I didn't think the CRJ-200 had the range. The only other routes that come close to matching the distance of DTW/SLC that DL's affiliates operate RJ on utilize the CRJ-700.