I-25 North at Exit 188B - Poplar St (WY-220). Approaching Exit 189 - US-20/US-26 West/To WY-220/Rawlins - Shoshoni. WY-220 is routed along Poplar St. but through traffic on WY-220, towards Rawlins, is encouraged to use Exit 189 and to follow US-20/US-26 and the West Casper Belt Route to bypass downtown Casper.