Boston has a lot of alternative channels for local print advertising: The Boston Globe, The Boston Herald, The Weekly Dig, Boston Metro, Boston Magazine, Barstool Sports, Bay Windows, Spare Change, and The Improper Bostonian... just off the top of my head. Plus every little neigborhood newspaper (Somerville News, Scout Somerville, etc.)

I can't speak for Providence, but I know Portland ME doesn't have anywhere near that number of print publications. It makes sense to me that local advertisers have few options in Portland and so can support a local paper, whereas in Boston you would need national advertisers to fill in. Sadly I don't think we've seen the end of the closures and bankruptcies for Boston publications yet.