What is the ProQuest Historical Newspaper database?  The short answer is that it is an index of the New York Times and Wall Street Journal.  That means that each article is given its own record that database users can search.  The New York Times is indexed from 1851-2001.  The Wall Street Journal is indexed from 1889-1987.  For later published articles, see LexisNexis Academic (New York Times) and ABI/INFORM Global (Wall Street Journal).

But the database offers more than just indexing.  The full-text of the articles is also included.  The text of the articles can also be searched which makes the database even more powerful.