The Newspaper Archive offers a massive online database of regional papers. It claims to have archived 895 million articles published in 747 cities over 240 years. In case you've run out of things to read on the web, here's a bottomless library.
I bought a ten-day pass to search for Jim Flora illustrations. Easy, right? Well, yes and no. NA's search engine uses OCR to find word strings in old newsprint that's been erratically scanned. It finds lots of "James Flora," but because there's no text correction, it probably misses the odd "Jannes Fiona" and "James F;ora." An imperfect process, but useful nonetheless. Aside from occasional local filler about Flora receiving an award or addressing a luncheon, most of the hits for our JF cited Sundays in the late 1950s and early 1960s. These turned out to be spot (and occasional feature) illustrations for weekly Parade Magazine supplements, which ran in hundreds of newspapers coast-to-coast. Parade seems to have been a meal ticket for Flora -- his illos often ran twice a month. We recognized some of the images because dozens of original mechanicals and tearsheets were retained by the artist and remain in the family archive. Newsprint does not store well, and because of the ephemeral nature of newspapers, existing copies in any condition are difficult to locate.
The tone of the Parade work is tame -- this is Flora during his transition from jazz hellcat to avuncular cartoonist. The change is reflected in all Flora's commercial work from the period, during which he was developing a new career as a children's book author/illustrator. His fine art from the 1960s retains an edge, but his public work appears to be laying the foundation for Bil Keane's Family Circus.