Portland, ME Night Sky Brightness (Reading Flagged)
Portland's reading looks wrong, and this site says so rather than hide it
The radiance figure on file for Portland is exactly 0.0, and a city of 69,568 people does not genuinely read zero light from orbit. That points to a sampling miss, the wrong coordinate, water, or unlit terrain right where the sample point landed, rather than an actual dark sky.
This is flagged instead of shown as a normal result because reporting it as "Portland's dark sky" would be reporting a data error as a fact, see the data quality guide for how this gets checked.
The nearest reliable reading to Portland
South Portland, ME is about 5 miles from Portland and has a trustworthy reading: suburban edge band. It's the closest usable stand-in until Portland's own figure is corrected.
Because Portland's own coordinate is what produced the bad reading, that distance figure is itself approximate, not a confirmed measurement.
Portland against the rest of the dataset
Portland, ME has a population of about 69,568, one of 3,206 US cities in this dataset, 3,187 of which have a usable brightness reading today.
The dataset and sampling method behind every one of those readings, flagged or not, are in the methodology guide.