Exaggerating just a little, aren't we? Where was that? Anchorage, Alaska? I grew up in Fargo, Dakota Territory, pretty far north and toward the west end of the Central Time Zone. Even with year-round DST, it was light by 8:45 am.
Before then, you'd have the Northern Lights sometimes, but that's another story.
The day begins later in the western part of the Mountain Time zone. Combine that with a range of mountains on the east side of the valley, the sun has to climb quite a bit into the sky to peek over the tops of the hills. So yes, the sun did rise around 10. Which meant that the first hour of class in Jr High was in the dark.