For the first time in history, the New York Mets will meet the Chicago Cubs in the NLCS, with the victor advancing to the World Series.
The Mets last appeared in the World Series in 2000 and last won the title in 1986. The Cubs' last World Series appearance was in 1945, and they haven't won a title since 1908. That's 107 years, kids. TL;DR – This NLCS is a very VERY big deal.
On top of the madness, Chicago and New York are two cities with a historic rivalry dating back to the first days of the United States, through the great skyscraper race of the early 1900s, and into present day.
I've lived in both cities, and here's how the rivalry breaks down today: Chicago is still a little bitter about being labeled "The Second City" during a fight with New York for a location bid for the Columbian Exposition (and again later in the 1950s), and doesn't understand why New York is considered by most to be a "better" city when Chicago has just as much culture, amazing cuisine, iconic buildings and public transportation that New York has.
New York, on the other hand, is too busy comparing itself to London and L.A. to pay Chicago much attention. Also, it's a common New York mentality to consider the city the ~only~ place to be. This New York superiority complex tends to just piss off Chicagoans even more, which makes sense.