Population from 2010 census; only National Parks are considered, not National Monuments, Lakeshores, Seashores, etc.; I used the select by location tool in ArcGIS to determine the correct cities. No park designated after January 1, 2018 is included.
In order to create a playlist on Sporcle, you need to verify the email address you used during registration. Go to your Sporcle Settings to finish the process.