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

🇺🇸 N8921Q - Boeing 737MAX 8 - Southwest Airlines SWA3321/WN3321, Chicago Midway (MDW) to Sacramento (SMF) - 4.4 mi away @ 38150 ft, heading WSW at 489 mph. Spotted 26x before! [03:56:01 PM CDT] #AC4F4C #N8921Q #B38M #SOUTHWEST #SWA3321 #WN3321 #ADSB #ADSBbot