Chronicling America is a great tool for finding and searching newspapers in most U.S. States.
Having trouble finding a specific newspaper? Search the Library of Congress database of offline newspapers to find out which institutions hold copies. Then find the institution's website, if any, and check if the newspaper is online. If not, contact the institution to find out how you can access the publication.
Daughters of the American Revolution (D.A.R.) Lineage Books contain pedigrees of descendants of soldiers who fought in the Revolutionary War, who have applied for D.A.R. Membership. New unknown ancestors could be revealed in these valuable records. Volumes 1-67 are here at your fingertips!
Early Western Travels, 1748-1846: A Series of Annotated Reprints of some of the best and rarest contemporary volumes of travel, descriptive of the Aborigines and Social and Economic Conditions in the Middle and Far West, during the Period of Early American Settlement, published in 1904 in 32 volumes including the index.
With a paid subscription (or 14-day free trial), FindMyPast allows you access to British and Irish records as well as passenger lists, military records and much more. It's definitely worth checking out!
My favorite places to go for free newspapers online.
Historical collections of the state of New York
Geographical descriptions of every township in the state, illustrated by 230 engravings and information about early settlers. Historical collections of the state of New York, by John Warner Barber and Henry Howe, 1846.
The State of New York has released their death index books, which they began printing in 1881. These books can help find or confirm the date and place of death, as well as the file number, for deaths that occurred after 1880. New York Death Records and Index
Images from probate records in various county Surrogate Courts in New York. The content of the probate records and their year range vary by county. Most records end in the 1920s with some indexes continuing to the year 1971.
The Compendium of American Genealogy, First Families of America, by Fredericak Adams Virkus, 1925, contains genealogies of thousands of early Americans. "A Genealogical Encyclopedia of the United States".