The last time the Cubs were in the World Series before last year was 1945 when they lost to the Detroit Tigers in 7 games.
Yes, 71 years is the current turnpike for longest absence from a finals series for a big 4 pro sports team and that’s up there with the Chicago/St. Louis/Phoenix/Arizona Cardinals NFL franchise that went from 1947 to Super Bowl XLIII (against the Pittsburgh Steelers) without a finals appearance. Current ones are:
NBA-Rochester/Cincinnati Royals/Kansas City/Sacramento Kings-1951-Won NBA championship same night as the 1951 NHL Toronto Maple Leafs did with Bill Barilko goal (player who died in plane crash in the following summer and Leafs did not win Stanley Cup until 1962 and that summer Barilko’s remains were finally found in Northern Ontario wilderness).
NFL-Detroit Lions-1957-longest absence from NFL final series and oldest team to have not yet appeared in a Super Bowl
NHL-Toronto Maple Leafs-1967-Last Stanley Cup title and Finals series appearance and last playoff year for the NHL Original Six era.
MLB-Montreal Expos/Washington Nationals-Entered MLB as an expansion team in 1969 and closest to World Series appearance was a loss to Los Angeles Dodgers for NL pennant in 1981. With the Cubs making the World Series last year and the other modern expansion teams like the California Angels, Texas Rangers, Houston Astros, NY Mets, San Diego Padres, and the Milwaukee Brewers winning at least one pennant, the Expos/Nats franchise is both the longest away from a Series appearance and oldest MLB expansion team to have not done so yet (followed by the 1977 Seattle Mariners).