As anyone who researches New York state historical newspapers knows - the big site is Old Fulton NY Post Cards which contains over 26 million searchable pages. But there are other large sites.
The old Northern New York site has changed to NYS Historic Newspapers.
The New York Heritage - New York State Newspapers project has many titles of their own, and they have produced a while ago a very nice tool that is based on a county map of the state. Not all sites (such as the Fulton site and Google News Archive) are included in the map, but since there are a few hundred newspapers available online on other sites, I would encourage you to make use of this very handy map.
It is very easy to use. Just click on a County Name and it will display newspapers available by City, Name of Newspaper (link), Years Covered, and the Resource where the newspapers can be searched.
The New York Heritage site can be found at New York Heritage - Newspapers
Yet another handy tool to make our research a bit easier. Thanks to New York Heritage for creating and making available this clickable map!