It starts with a single shot, followed by a series of volleys spaced seconds apart — a dazzling display of every color of the spectrum that forms blooms and smiley faces. The explosions bounce off the mountains encircling town, creating a series of lingering echoes. The grand finale is a nearly two-minute spasm of sound and light that fill the box canyon.

And then it’s over. The Fourth of July fireworks show that caps a day of festivities in Ouray lasts less than 30 minutes. But it’s a pr...