The first presidential library was dedicated in 1941 by President Franklin D. Roosevelt. Following Roosevelt's example, Herbert Hoover and Harry Truman both opened presidential libraries to hold their donated papers. Now, the National Archives administers 13 presidential libraries, with a 14th in the planning stages.
“This library is a congressionally designated depository for U.S. Government documents. Public access to the government documents collection is guaranteed by public law. (Title 44 United States Code)”