Premise: Snake Pass is a hill pass in the Derbyshire section of the Peak District, crossing the Pennines between Glossop and the Ladybower Reservoir at Ashopton. The road was engineered by Thomas Telford and opened in 1821. The pass carries the A57 road between Manchester and Sheffield, but it is no longer the main signposted route between those two cities.
Hypothesis: Snake Pass used to be a major road.