Where was Mr. Mercedes filmed?
2017-2019 American crime drama television series
Mr. Mercedes (2017–) was filmed in Charleston, 1 place named in its Wikipedia article's Filming section, in the United States. Wikidata records no filming location for it at all, so the article is the only recorded source. Each place says where its claim comes from.
Places per Wikipedia's Filming section
Wikipedia’s Filming section names 1 place. Each links to the sentence that says so.