Map of the St. Louis area showing the position and track of the aircraft described in the post.

🇺🇸 N737NK - AIRBUS A321neo - Spirit Airlines NKS623/NK623, Cancun (CUN) to Chicago O'Hare (ORD) - 3.9 mi away @ 33425 ft, heading NNE at 547 mph. Spotted for first time! [05:51:11 PM CDT] #A9E642 #N737NK #A21N #SPIRIT_WINGS #NKS623 #NK623 #ADSB #ADSBbot