Set the Search Scope to "Articles & More" and the desired Material Type to "Articles". This will return results for articles published in newspapers, magazines, and scholarly journals. There is no way to limit results to only newspapers.
You may search for newspaper articles in collections limited to newspapers published in the United States:
Find American newspapers from the late 17th century to the late 20th century. Search or browse by dates and eras, newspaper titles, places of publication, and article types. Includes the African American Newspapers, 1827-1998 collection.
Nexis Uni features more than 15,000 news, business and legal sources from LexisNexis—including U.S. Supreme Court decisions dating back to 1790—with an intuitive interface that offers quick discovery across all content types, personalization features such as Alerts and saved searches and a collaborative workspace with shared folders and annotated documents.
Check out this series of short videos for a demonstration of how to use Nexis Uni:
An integrated search interface that includes the following newspaper collections: 17th and 18th Century Burney Collection, British Library Newspapers, Nineteenth Century U.S. Newspapers, The Times Digital Archive, 1785-1985.