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

🇺🇸 N921NN - Boeing 737NG 823/W - American Airlines AAL328/AA328, Dallas-Fort Worth (DFW) to Chicago O'Hare (ORD) - 4.4 mi away @ 36950 ft, heading NE at 546 mph. Spotted 43x before! [09:43:28 AM CDT] #ACC31A #N921NN #B738 #AMERICAN #AAL328 #AA328 #ADSB #ADSBbot