The five all time longest championship droughts now (in the big four) are now:
1947-Chicago/St Louis/Phoenix/Arizona Cardinals-NFL-went from 1947 to 2008 without being in an NFL Final or Super Bowl
1948-Cleveland Indians-MLB-in 1954, 1995, 1997, and 2016 World Series
1951-Rochester/Cincinnati Royals/Omaha/Kansas City/Sacramento Kings-NBA-also first and only NBA finals series appearance
1957-Detroit Lions-NFL-last NFL final appearance, have never been to a Super Bowl
1958-St. Louis/Atlanta Hawks-NBA-last appearance in NBA Final Series was 1961.
Note: Longest drought in NHL is the Toronto Maple Leafs-last Stanley Cup championship and Finals Series appearance was against the Montreal Canadiens in 1967 (last Original Six season before modern expansion).
Interesting information, thanks.