Major League Sports' Longest Title Droughts

Note: I am only including those teams that have gone at least 25 years. I am counting from either their last title, or, if they have never won one, from the first game in franchise history. 

New York Tri-State Area teams are in bold. Droughts that have ended are in italics.

25 to 30 years:
MLB Oakland Athletics: 25 years even, 1989-present.
NHL Calgary Flames: 25 years, 5 months, 1989-present.
MLB Los Angeles Dodgers: 26 years even, 1988-present.
NBA Houston Rockets: 26 years, 8 months, 1967-1994.
MLB Cincinnati Reds: 27 years, 6 months, 1882-1919.
MLB Cleveland Indians: 28 years even, 1920-1948.
MLB Philadelphia Phillies: 28 years even, 1980-2008.
NFL Chicago Bears: 28 years, 9 months, 1986-current.
NFL Green Bay Packers: 29 years even, 1968-1997.
MLB Kansas City Royals: 29 years even, 1985-current.

30 to 40 years:
MLB Detroit Tigers: 30 years even, 1984-current.
NFL New York Giants: 30 years, 1 month, 1956-1987.
NBA Philadelphia 76ers: 30 years, 4 months, 1983-current.
NBA Dallas Mavericks: 30 years, 6 months, 1980-2011.
NHL Minnesota North Stars/Dallas Stars: 31 years, 6 months, 1967-1999.
NBA Detroit Pistons: 31 years, 8 months, 1957-1989.
NBA San Antonio Spurs: 31 years, 8 months, 1967-1999.
NFL Oakland Raiders: 30 years, 9 months, 1984-current.
MLB Baltimore Orioles: 31 years even, 1983-current.
NHL New York Islanders: 31 years, 5 months, 1983-current.
NFL New England Patriots: 32 years, 5 months, 1960-2002.
MLB Detroit Tigers: 34 years, 6 months, 1901-1935.
MLB Cincinnati Reds: 35 years even, 1940-1975.
MLB Pittsburgh Pirates: 35 years even, 1925-1960.
MLB Pittsburgh Pirates: 35 years even, 1979-current.
NFL San Francisco 49ers: 35 years, 4 months, 1946-1982.
NBA Seattle SuperSonics/Oklahoma City Thunder: 35 years, 4 months, 1979-current.
NBA Washington Bullets/Wizards: 36 years, 4 months, 1978-current.
NBA Portland Trail Blazers: 37 years, 4 months, 1977-current.
NFL Denver Broncos: 37 years, 5 months, 1960-1998.
NFL Seattle Seahawks: 37 years, 5 months, 1976-2014.
MLB Seattle Mariners: 37 years, 6 months, 1977-current.
MLB Milwaukee/Atlanta Braves: 38 years even, 1957-1995.
NHL Boston Bruins: 39 years, 1 month, 1972-2011.
NBA Golden State Warriors: 39 years, 5 months, 1975-current.
NHL Philadelphia Flyers: 39 years, 5 months, 1975-current.

40 to 50 years:
MLB St. Louis Cardinals: 40 years even, 1886-1926.
NBA New Orleans/Utah Jazz: 40 years even, 1974-current.
NHL Washington Capitals: 40 years even, 1974-current.
NBA New York Knicks: 41 years, 5 months, 1973-current.
NFL Miami Dolphins: 41 years, 9 months, 1973-current.
MLB Philadelphia/Kansas City/Oakland Athletics, 42 years even, 1930-1972.
NHL Detroit Red Wings: 42 years, 2 months, 1955-1997.
NFL Pittsburgh Steelers: 42 years, 5 months, 1933-1975.
MLB Texas Rangers: 42 years, 6 months, 1972-current.
MLB Boston/Milwaukee Braves: 43 years even, 1914-1957.
NBA Milwaukee Bucks: 43 years, 5 months, 1971-current.
NBA Buffalo Braves/San Diego/Los Angeles Clippers: 43 years even, 1970-current.
NFL New Orleans Saints: 43 years, 5 months, 1967-2010.
NBA Cleveland Cavaliers: 44 years even, 1970-current.
NHL Vancouver Canucks: 44 years even, 1970-current.
NHL Buffalo Sabres: 44 years even, 1970-current.
NHL Los Angeles Kings: 44 years, 8 months, 1967-2012.
NFL Kansas City Chiefs: 44 years, 9 months, 1970-current.
MLB Milwaukee Brewers: 45 years, 6 months, 1969-current.
MLB San Diego Padres: 45 years, 6 months, 1969-current.
MLB Montreal Expos/Washington Nationals: 45 years, 6 months, 1969-current.
NFL New York Jets: 44 years, 9 months, 1969-current.
NBA Phoenix Suns: 46 years even, 1968-current.
NBA Indiana Pacers: 46 years even, 1967-current.
NFL Cincinnati Bengals: 46 years, 1 month, 1968-current.
NBA Denver Nuggets: 47 years even, 1967-current.
NBA New York/New Jersey/Brooklyn Nets: 47 years even, 1967-current.
NHL St. Louis Blues: 47 years even, 1967-current.
NHL Toronto Maple Leafs: 47 years, 6 months, 1967-current.
NFL Los Angeles/St. Louis Rams: 48 years, 1 month, 1951-2000.
NFL Atlanta Falcons: 48 years, 1 month, 1966-current.
MLB Los Angeles/California/Anaheim/Los Angeles Angels: 48 years, 6 months, 1962-2010.
NHL Chicago Blackhawks: 49 years, 2 months, 1961-2010.
NFL Cleveland Browns: 49 years, 10 months, 1964-current.

50 to 60 years:
MLB Houston Astros: 52 years, 6 months, 1962-current.
NFL Minnesota Vikings: 53 years, 1 month, 1961-current.
NFL Philadelphia Eagles: 53 years, 10 months, 1960-current.
NFL Buffalo Bills: 54 years, 1 month, 1960-current.
NFL San Diego Chargers: 54 years, 1 month, 1960-current.
NFL Houston Oilers/Tennessee Titans: 54 years, 1 month, 1960-current.
NHL New York Rangers: 54 years, 2 months, 1940-1994.
MLB Brooklyn Dodgers: 55 years even, 1900-1955.
MLB New York/San Francisco Giants: 56 years even, 1954-2010.
NBA St. Louis/Atlanta Hawks: 56 years, 6 months, 1958-current.
NFL Detroit Lions: 56 years, 10 months, 1957-current.

60 years or more:
MLB Washington Senators/Minnesota Twins: 63 years even, 1924-1987.
NBA Rochester/Cincinnati Royals-Kansas City/Sacramento Kings: 63 years, 4 months, 1951-current.
MLB St. Louis Browns/Baltimore Orioles: 65 years, 4 months, 1901-1966.
MLB Cleveland Indians: 66 years even, 1948-current.
NFL Chicago/St. Louis/Arizona Cardinals: 66 years, 10 months, 1947-present.
MLB Boston Red Sox: 86 years, 1 month, 1918-2004. *
MLB Chicago White Sox: 88 years even, 1917-2005.
MLB Philadelphia Phillies: 98 years, 6 months, 1883-1980.
MLB Chicago Cubs: 114 years even, 1908-current.

The asterisk next to the Red Sox refers not just to the fact that they cheated to win the World Series in 2004 (and 2007, and 2013), but to the fact that the 1918 MLB season was shortened on orders from the federal government, due to World War I, and the World Series was held in September instead of the usual October.

If you count the current Ottawa Senators franchise with the old one, it's been 87 years, 6 months -- but then, there was a drought of 58 years, 6 months when they didn't even have a team. You could do the same thing with the Baltimore Orioles: An NL team with that name was World Champions in 1896, and the current AL team with that name won in 1966, 70 years later.

*

Average current droughts (for those cities with at least 2 teams):

Boston: 5 years, 2 months.
Los Angeles: 13 years, 4 months.
Pittsburgh: 15 years, 5 months.
Nashville: 15 years, 6 months.
Baltimore: 16 years, 5 months.
Miami: 18 years, 5 months.
New Orleans: 18 years, 11 months.
Seattle: 19 years, 1 month. (Before the Super Bowl win, it was 37 years, 2 months.)
Dallas: 20 years, 6 months.
St. Louis: 21 years, 5 months. (The Blues dragging them down.)
San Francisco Bay Area: 23 years, 1 month.
Denver: 24 years, 5 months. (The Nuggets dragging them down.)
Detroit: 25 years, 10 months.
New York Tri-State Area: 25 years, 11 months. (Thanks, Jets, Knicks and Nets.)
Indianapolis: 26 years, 10 months.
Minnesota: 28 years, 10 months.
Milwaukee/Green Bay: 30 years, 6 months. (The Packers keeping it even that low.)
Chicago: 32 years, 4 months.
Philadelphia: 32 years, 8 months.
Kansas City: 36 years, 9 months.
Cincinnati: 36 years, 10 months.
Atlanta: 37 years, 5 months.
Houston: 39 years even.
Toronto: 43 years, 6 months.
Washington: 45 years, 1 month. (Only the Redskins holding that down.)
Buffalo: 47 years, 1 month.
Phoenix: 49 years, 8 months.
San Diego: 49 years, 10 months.
Cleveland: 52 years, 7 months.