This is Jenny Lake in Grand Teton National Park.
This was probably the best sunset of the entire Colorado / Wyoming trip. About 15 minutes after the sun disappeared, the skies basically erupted with orange and red hues streaking from south to north. It lasted only about 2 minutes but that was enough.
On the right side of the photo, you can possibly make out an area of burned out trees affected by 2016 wildfires that hit both Grand Teton and Yellowstone.