Some sources for text.  Please feel free to add other sources in the comments section below, and I will integrate them into the page. 

Digitized text

• HathiTrust - https://www.hathitrust.org/
  • Download PDFs of full-view books (requires login)
  • APIs available for bibliographic info - https://www.hathitrust.org/data
  • HTRC - https://analytics.hathitrust.org/
    • Good for working with in copyright digitized books
    • Worksets allow you to assemble a corpus that satisfies your research interests from volumes in HathiTrust
    • Datacapsule - allows command line and GUI analysis of worksets of your choice
    • Structured data sets - https://analytics.hathitrust.org/datasets
  • Internet Archive - https://archive.org/details/texts
  • Early English Books Online - https://eebo.chadwyck.com/home
  • Library subscribed databases -
    
    • ex: Proquest/EBSCO/Gale - library selectors can negotiate purchase of texts of interest;
    • Reference staff can put you in touch with key personnel who can negotiate appropriate extracts for you.

Transcribed text

• Project Guttenberg - https://www.gutenberg.org/

Born digital text

Look for API’s (Application Programming Interface) which will more easily assist you in downloading desired text.

• Online news - look for APIs from news server
• Twitter - https://developer.twitter.com/en/docs/api-reference-index
• Facebook -
  • Documentation - https://developers.facebook.com/docs/
  • Tools - https://developers.facebook.com/tools-and-support/
  • Email - Download an account in mbox format (which will be most open)