Good post, Jim! This is a vitally important safety precaution!

Especially for fall and winter hikes, it's good to have a turnaround time to get back to the trailhead well in advance of darkness. Particularly on the Oregon side of the Columbia River Gorge, in the north-facing forests and deep side canyons, it's getting pretty dark even before sunset. If you calculate your return time at civil twilight (1/2 hour after sunset), you'll be in complete darkness, particularly on the dim, cloudy days that occur on most winter days.

Of course with most of the Columbia Gorge trails still closed due to the 2017 Eagle Creek fire, the question is not so critical. I suspect that as those trails open back up, though, we'll see an increase of SAR callouts due to people still on the trails after dark! It's so easy to walk off a cliff in that area!