If you've ever tried to locate one, you know that finding copies of TV and radio news transcripts and recordings can be fairly difficult. These three sources, however, may have just what you need.

Vanderbilt TV News Archive
Contains more than 30,000 individual network evening news broadcasts from the major U.S. national broadcast networks: ABC, CBS, NBC, and CNN, and more than 9,000 hours of special news-related programming including ABC's Nightline since 1989.

Library of Congress, Recorded Sound Reference Center, Radio, and SONIC (Sound Online Inventory & Catalog)
Among other things, includes NBC Collection (1930s-1980s, including tens of thousands of World War II-related broadcasts), Armed Forces Radio and Television Service (AFRTS) (1942-1998), Office of War Information (OWI) (1942-1945), National Public Radio (NPR) (The cultural programming portions of NPR broadcasts,1971-1992)

Visual and Sound Archives, State Historical Society of Wisconsin
Includes NBC Records, Script and Recording Library (1921-1969) which contains radio scripts, TV scripts, and recordings