Fairmont Hot Springs, accessible via S-441 is the first exit in Silver Bow County on I-90, as the highway starts to turn back towards the east. Ramsay is located in the southwest corner of the interchange where I-15 becomes concurrent with I-90 through Butte. On the western edge of Butte, I-115 continues east into town, as I-15/90 turns southeast, bypassing most of downtown Butte. An interchange with MT 2 serves the Bert Mooney Airport before I-15/90 split just east of Butte, with I-15 continuing north over the Continental Divide over the high Elk Park Pass, which straddles the Silver Bow-Jefferson County border. I-90 heads south then east, also entering Jefferson County, passing over the divide at Homestake Pass which is high. After traveling the pass, an emergency escape ramp can be found on the highway's eastbound lanes. Jefferson County has interchanges with S-399 east of Pipestone, Montana and S-359 east of Cardwell before meeting the Jefferson-Broadwater County border.