 William Safire of The New York Times wrote that " have a nice day " first appeared in the 1948 film A Letter to Three Wives . The American Heritage Dictionary of Idioms stated that " have a nice day " first came into being in 1920 , and the phrase and its variants became widely used after the 1950s . In 1964 , Carol Reed of WCBS @-@ TV spread the phrase in the New York metropolitan area by closing her weather reports with " have a happy day " , which , according to Safire , is a variant of " have a nice day " . The 1960s saw the phrase " have a good day " become prevalent and supersede " happy day " . Numerous hippies , when parting , told each other to " have a nice day " or " have a beautiful day " . In 1970 , " have a nice city " was a mayoralty slogan in San Francisco . In 1972 , during the Vietnam War , family members of POW / MIA members of the American armed forces participated in South Boston 's Saint Patrick 's Day march . They carried a black banner that read " POW / MIA Families Never Have a Nice Day " . They received scowls and jeers from a hostile crowd . One woman said , " They should be shot for bringing this here . " 
