Which MLS Cup semifinalist city has the longest title drought?

Atlanta United - Dejected - 2017

There will be an MLS Cup-winning celebration on December 8 in New York, Atlanta, Portland or Kansas City. But, one of those four cities is much longer overdue for a parade than the others.

Atlanta's championship blues and heartbreak have been oft-discussed, most recently when then the Falcons blew a 28-3 lead in a loss to the New England Patriots in Super Bowl LI.

When was the last title for each of the cities? 

Atlanta Braves (MLB)
New York City
New York Giants (NFL)
Kansas City
Kansas City Royals (MLB)
Portland Thorns (NWSL)

Despite having fewer teams in major professional sports, both Kansas City and Portland have tasted success much more recently than New York, which is home to 11 major professional teams. 

Atlanta United have already faced disappointment this season when the New York Red Bulls caught them in dramatic style on Decision Day presented by AT&T to win the Supporters' Shield.

Can Atlanta bring a long overdue title parade to their city? Can the Red Bulls break their own personal title drought? Or will it be either Sporting Kansas City or the Portland Timbers, who have both have won MLS Cup this decade?

Audi 2018 MLS Cup playoff action resumes Sunday with the first leg of the Conference Championship.