TimesMachine - A browser-based digital replica of all issues from 1851 to 2002. Registered users through group subscriptions are able to download 5 PDFs per day, with unlimited browsing.
The New York Times Article Archive - Accessible via search, the archive provides partial and full-text digital versions of articles from 1851 to today and redirects to TimesMachine where applicable.
Historical New York Times database via ProQuest - Full-text searchable page-images of the Times published edition from 1851-2015.