American Airlines has a low one fare between Chicago ORD and New York JFK at $40.10 one way. There are limited departure dates starting in JFK or ORD at this fare. Google Flights for JFK-ORD shows six dates between Dec 2-15 with $40 fare and ORD-JFK is only $40 on three dates Dec 2,3 and 9th. Other low fare dates to mid-December are priced from $59 to $82 one-way.
American Airlines Chicago ORD – New York JFK
$80.20 Wednesday December 2 – Saturday December 5
American Airlines also has Chicago – Boston and Chicago – Philadelphia at $80.20 round trip on these same Dec 2-5 dates.