Recently I became aware of a new service, provided by a company in New Zealand, that provides what I like to call a "combo" research methodology for searching multiple newspapers at one time.
I have done several YouTube videos and tutorials about navigating digital newspaper repositories and sites. They all have one thing in common - the site is dedicated more than likely to a U.S. state or Canadian province, with multiple newspapers from that geographical entity.
Elephind takes it one step further and eliminates the geographical boundary - they allow searching of several of these geographically "bounded" repositories at one time.
Currently they have over 1,000 newspaper titles that they make available for searching. The largest two are from the National Library of Australia (Trove), and the U.S. Library of Congress (Chronicling America), and they include titles from Singapore and New Zealand, as well as other U.S, collections. Certainly you could search each of these sites individually, yet a search of all at one time might be appropriate at times.
I know I will be watching this site as it continues to grow. If you are interested in different ways to access newspapers, you might want to also. They can be found at www.elephind.com. Also if you visit the site you will be able to discover what an elephind is!