Where was Brotherhood of Death filmed?

1976 film by Bill Berry

Brotherhood of Death (1976) was filmed in Montgomery County, Bowie and Smithfield, 3 places named in its Wikipedia article's Production 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.

See them on the map → Wikipedia Source data

Places per Wikipedia's Production section

Wikipedia’s Production section names 3 places. Each links to the sentence that says so.