Scots-Irish is almost synonymous with hillbilly in the US. Scots migrated first from Scotland to Ulster (not Northern Ireland), then to the US, often entering through Philadelphia, walking west until they hit properly tilted country, then working their way down the Appalachian Mountains (at the time America’s “backcountry”). But many Scots immigrants never detoured through Ulster. More importantly, as David Hackett Fischer points out in Albion’s Seed, a large portion of that immigration wave were from northern England. They weren’t from Scotland at all.