Portland, TN Night Sky Brightness
Portland, TN: how dark is the sky here?
Portland reads as suburban on this dataset's scale. Light dome dominates much of the sky. Only the brightest stars and planets stand out clearly. Portland's sky is brighter than 53.2% of the 3,206 cities in this dataset.
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 - see the Bortle scale guide for where they can disagree.
The nearest darker sky to Portland
The closest place in this dataset with a meaningfully darker sky is Franklin, KY, roughly 9 miles away in a straight line, rated suburban edge. Road distance will be more.
Franklin, KY is itself still a measured city, not a designated dark-sky park, this only compares against the 3,206 places this dataset covers.
How Portland compares nationally
Portland, TN has a population of about 13,651, one of 3,206 US cities of 10,000 or more residents in this dataset. Portland places 1,697 of 3,206 cities in this dataset's darkest-to-brightest order, ranked by the method in the methodology guide.