WASHINGTON — The Library of Congress has amassed about 170 billion tweets since 2010, when it began archiving the messages.

And now Twitter is donating to the library its own archive, going back to the first tweet, posted in 2006.

Gayle Osterberg, the library’s director of communications, yesterday blogged that its volume of tweets has grown from 140 million daily in February 2011 to nearly half a billion a day as 2012 came to a close.

She said the library may work with a private partner to provide access because its own search technology is relatively slow.