National news is a subfield of journalism that covers events, issues or developments that affect the entire country. It is distinguished from international news, which usually involves events in other countries and the operation of multilateral organizations. This field can also include war journalism, although that is more typically a subfield of world news.
The emergence of mass media in the 19th century dramatically changed the role of newspapers, which moved beyond the cities of their original bases and became profitable powerhouses of advocacy, muckraking and sensationalism. Technological change in the 1920s led to the development of radio, and television and the internet further transformed journalism in recent decades.
During the early days of television, local newscasts had slow paces and low story counts. But the outbreak of World War II led to irregularly scheduled quasi-network newscasts on NBC, originating from WNBT in New York City and reportedly fed to WPTZ in Philadelphia and WRGB in Schenectady. This was a precursor of the regularly scheduled NBC Television Newsreel, which aired filmed news highlights with narration.
Early weekday mornings, ABC and CBS offer half-hour programs that are aired on most stations. NBC airs the higher-rated Early Today, while ABC offers Good Morning America First Look and CBS News This Morning. In addition, both networks feature newsmagazine programs on weeknights at 9PM ET: 20/20 on ABC and Dateline NBC on NBC. The Public Broadcasting Service (PBS) offers a variety of national news and public affairs programs on its 349 member stations, including PBS NewsHour and Frontline.