http://spiderbites.nytimes.com/
Click on any year there from 1851-1922, and you can browse thousands of articles from that year and download a PDF scan of the orginal article.
HOWEVER.....
As I was about to post this, raving about what a great source it is for finding PD non-fiction short works, I clicked around on a few more articles, and quickly ran into a snag. Apparently, these pre-1923 articles count towards your "five free articles a month." Is this even ok??? Do PD laws apply differently towards newspapers? I'd like to write NYT an angry letter or something, scolding them for restricting access to information that is clearly public domain and should be freely available to anyone interested in history, society, culture, whatever... But I'm sure they, at least, feel like the law is on their side or they wouldn't do this. Here is their policy on this, as found in their FAQ:
For nonsubscribers, articles from the New York Times archives from 1923 through 1980 are $3.95 each. Views of archived articles outside that date range are free but still count toward the 5-article monthly limit.