Since this is one of the busiest domestic corridors in the country, pricing on flight tickets from chicago to new york tends to be pretty competitive — but it still swings based on how far out you book, which day you fly, and which airport pair you choose. Basic economy fares booked a few weeks in advance are usually the most budget-friendly option, while last-minute or peak-season tickets (holidays, summer weekends) can cost noticeably more.
A few cost-saving moves worth trying:

• Compare all three NYC airports (JFK, LGA, EWR) instead of just one
  

• Fly midweek rather than Friday or Sunday
  

• Consider budget carriers alongside the legacy airlines for extra savings
  

• Set fare alerts to catch price drops automatically