I can't say enough about the good intentions of Google News Archive Search, which offers access to hundreds of years of news articles. This is a fantastic resource and it's high time someone did it. The project will provide the impetus to many organizations to open up their archives, because they become valuable when you have the context of history.
But I tried it and found it needs work. The event I used as my historical guinea pig was the Boston Molasses Flood of 1919, a notably bizarre and oft News Archive Search a fantastic resource and it's high time someone did it. forgotten disaster involving two million gallons of scalding hot goo. I searched on the phrase Boston Molasses Flood and, in the initial results narrowed the timeframe down to the decade when the flood happened, the 1910s. What I got was a list of modern articles rather than articles from 1919, when the flood happened. There were also articles in the Boston Globe about a 1989 molasses flood in Nebraska (who knew this was such a problem?).
The results need to be framed within the decades you select, not about the decade. The former gives you source material, the latter is only history and not very useful history because one needs to understand not just the event itself but the interpretation offered by the historian, who may be putting their own spin on the story.
Google did much better with the phrase James Garfield dies constrained to the years 1880-1882. Garfield, in case you forgot, was shot by a madman and lingered for several months in Long Branch, New Jersey before dying of his wounds in September 1881. Here, we get an inventory of 2,840 articles, the first pages dominated by stories and editorials written at the time rather than about the time, though many about other people dying and Garfield's alleged involvement in a scandal involving Credit-Mobiliare.
These, though, are problems of early-stage software and building an index, not faults with the idea its execution. Bravo, Google, for this first effort. Keep it going, I'll be a user.