Social media collections:

• Harvard Dataverse, https://dataverse.harvard.edu/dataverse/harvard
• Web Archives for Historical Research Group, https://zenodo.org/communities/wahr/?page=1&size=20
• Web Archives for Historical Research Group Dataverse, https://dataverse.scholarsportal.info/dataverse/wahr
• UK Government Web Archive, Social Media Archive Search, https://webarchive.nationalarchives.gov.uk/social/search/

Twitter collections (please observe supplementary notice below):

• The DocNow Catalog, https://catalog.docnow.io
• US presidential election 2020 dataset by Emily Chen et. al.: echen102/us-pres-elections-2020, corpus here: https://github.com/echen102/us-pres-elections-2020, article here.
• #metoo Digital Media Collection, Schlesinger Library (with a reference and explanation of Hydrator, please also see notice below on this page), https://www.schlesinger-metooproject-radcliffe.org/how-to-use-the-twitter-data
• Digital Narratives of Covid-19, dh-miami/narratives_covid19, corpus here: https://github.com/dh-miami/narratives_covid19/tree/master/twitter-corpus - with a reference and explanation of Hydrator, https://covid.dh.miami.edu/2020/06/11/hydrating-tweetsets - please also see notice below on this page),

Important notice: Twitter datasets may be disseminated only as lists of Tweet IDs. In order to retrieve the tweets and their content as a workable dataset, one may use the application Hydrator.