I use the Library of Congress site for most of my old newspaper reading. Here is the link to the news paper mentioned in this post so you can see how it gives it to you. Also there is a search box at the top of the page and you can just type in a date or date range and it will give you list of what they have within the dates to click on look at it. It might not always be newspapers, it can be books, or declassified documents that are old.
https://www.loc.gov/resource/sn82014760/1861-03-07/ed-1/?sp=2&r=0.175,0.309,0.95,0.472,0