Thomas worked for the United Press and post-1958 successor United Press International (UPI) for 57 years, first as a correspondent, and later as White House bureau manager. She then served as a columnist for Hearst Newspapers from 2000 to 2010, writing on national affairs and the White House. Thomas was the first female officer of the National Press Club, the first female member and president of the White House Correspondents' Association and the first female member of the Gridiron Club. She wrote six books; her last (with co-author Craig Crawford) was "Listen Up, Mr. President: Everything You Always Wanted Your President to Know and Do" (2009).