Google News (Newspapers) Archive Search
Google now lets you search a news archive that consists exclusively, it seems, of newspaper archives, digital or scanned, provided they aren’t held behind a paywall. This may have been available before now, but I’ve only become aware of it today. And I have to say that for anyone seeking to inquire into the last hundred years or so, this is a treasure trove. Google doesn’t say how many newspapers are in the database, but I count something like 120 beginning with “A” alone (among which is a plentiful supply of Canadian publications). For each publication, you’re told how many issues are available and the date range as well.
There’s a help page that explains a little bit about searching in this newspaper archive. Current Google News goes back only 30 days; after that you need to go to the archive, and as the help page explains, a search in Google might look like this: [site:google.com/newspapers searchterm]. (Note that the URL google.com/newspapers by itself leads nowhere; the URL for the archive is news.google.com/newspapers.)
[Hat tip: @coyne]




See also Wikipedia’s master list of online newspaper archives. Note that there is even a section for Canada. [Hat tip: SearchReSearch].