There are affiliated centers in all 50 states and the District of Columbia. On May 1, 2007, state center representatives participated in an idea sharing session at the Library. It was marked by lively discussion on an array of topics including state center participation in the Pavilion of States at the National Book Festival, state book festival and awards programs, One Book community reading projects, and the center's two national signature projects, Letters About Literature and River of Words.

Each state center works with the Library of Congress to promote books, reading, and libraries as well as the state's own literary and intellectual heritage. Each also develops and funds its own operations and projects, making use of Library of Congress reading promotion themes and assistance when appropriate and available. When its application is approved, a state center is granted affiliate status for three years. Renewals are for three year periods. In 2007, renewal applications were approved from Alabama, California, Connecticut, Georgia, Idaho, Illinois, Louisiana, Maine, Nevada, Ohio, Vermont, and West Virginia.