The library said it isn't prepared to collect every single tweet anymore because of some of Twitter's recent changes, such as the adoption of embedded images and video, as well as support for longer tweets. Nor does the library see itself as a “comprehensive” collector, it said.
In a blog post Tuesday, the Library of Congress said that beginning Jan. 1, it will collect a more limited set of tweets in an effort to better fulfill its traditional role as a curator of U.S. history.
“Generally, the tweets collected and archived will be thematic and event-based, including events such as elections, or themes of ongoing national interest, e.g. public policy,” the library wrote in a white paper accompanying the blog post.
The act of preserving tweets can often be a valuable service. Not only do records of old tweets offer insight into the public mood at a particular point in time, but in some cases, they can also help hold public figures accountable. For example, third-party services such as Politwoops have successfully unearthed important tweets elected officials sought to delete and bury.
The Library of Congress said it won't get rid of its existing archive. People can still use the 2006-2017 Twitter archive to get a glimpse at the early years of social media and its evolution into a worldwide phenomenon.