Grantsville, UT: how dark is the sky here?

Satellite radiance puts Grantsville in the dark sky band. Among the darkest skies of any US city in this dataset. The Milky Way should be visible overhead on clear, moonless nights. Only 1.6% of the 3,206 cities measured here read darker than Grantsville.

This comes from a satellite measuring light radiating upward, not a person's eyes on the ground, so it isn't the same as a Bortle class, though the two track each other closely.

Grantsville is already about as dark as this dataset gets

Nothing in this dataset's 3,206 US cities measures a darker sky than Grantsville. That doesn't mean nowhere is darker, unincorporated land and wilderness aren't part of this dataset at all, only incorporated cities of 10,000 people or more.

How Grantsville compares nationally

Grantsville, UT has a population of about 15,682, one of 3,206 US cities of 10,000 or more residents in this dataset. Grantsville places 53 of 3,206 cities in this dataset's darkest-to-brightest order.