Alberta's 1 to 216 series of provincial highways are Alberta's main highways. They are numbered from 1 to 100, with the exception of the ring roads around Calgary and Edmonton, which are numbered 201 and 216 respectively. The numbers applied to these highways are derived from compounding the assigned numbers of the core north–south and east–west highways that intersect with the rings roads. In Calgary, Highway 201 is derived from the north-south Highway 2 and the east-west Highway 1. In Edmonton, Highway 216 is derived from the same north-south Highway 2 and the east-west Highway 16.