Watch World News Tonight Prime With David Muir

Harry Reasoner and Howard K. Smith had co-anchored the ABC Evening News from December 1970. In 1975, Reasoner assumed sole anchor responsibilities until his pairing with Barbara Walters, the first female network anchor, in Oct. 1976. On July 10, 1978, Roone Arledge, head of ABC's news and sports divisions, launched World News Tonight with a trio of anchors -- Frank Reynolds, Peter Jennings, and the late Max Robinson. From 1983 to 2005, the program was anchored by Peter Jennings. Following Jennings' death, Elizabeth Vargas and Bob Woodruff were named as co-anchors. Woodruff was severely wounded in January 2006 while reporting from Iraq. Vargas stepped down for maternity leave in May 2006 and Charles Gibson was named as permanent anchor. David Muir took over for Diane Sawyer on September 1, 2014 as permanent and sole anchor.