What interstate does Interstate 15 cross after Butte, Montana?
Silver Bow, Butte:  It lies near the interchange of Interstate 15 and Interstate 90, near Rocker. Interstate 15 in Montana: In the U.S. state of Montana, Interstate 15 continues onward from Idaho for nearly 400 mi through the cities of Butte, Helena and Great Falls, intersecting with Interstate 90, Interstate 115 and Interstate 315.
Interstate 115