From the American Library Association (ALA):
First sponsored in 1958, National Library Week is a national observance sponsored by the American Library Association (ALA) and libraries across the country each April. It is a time to celebrate the contributions of our nation’s libraries and librarians and to promote library use and support. All types of libraries – school, public, academic and special – participate.
For more information about National Library Week, go to the @ your library website.