Google has added the ability to search through more than 200 years of historical newspaper archives to its Google News service. Google News Archive Search generates a timeline of stories that match a particular subject or keyword, with hits arranged chronologically by date.

Sources include articles from free historical news sources as well as snippets of articles available for a fee or via subscription, from newspapers like The New York Times and the The Guardian. If there are many articles, then results are grouped by time period, with timeline links in the left-hand column. I highly recomment advanced search to help narrow down results.

In my initial searches I found Google's Historical Newspaper Search to be a useful way to dig up old newspaper articles from multiple sources. In many cases, for the fee-based articles, I was then able to access them through one of the old newspaper databases subscribed to by my library or genealogical societies of which I'm a member. I did find it a bit unusual that results from Ancestry.com kept popping up, however. They were links to historical records, such as WWI Draft Registration Cards, but not newspapers.

More About Historical Newspapers:
How to Find & Use Newspapers in Genealogical Research