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

🇺🇸 N618UX - Embraer EMB-175 LL - United Express SKW5728/OO5728, St Louis Lambert (STL) to San Francisco (SFO) - 3.5 mi away @ 12750 ft, heading WNW at 321 mph. Spotted 21x before. [08:51:19 AM CDT] #A80E4E #N618UX #E75L #SKYWEST #SKW5728 #OO5728 #autopilot #Landing #Departure #ADSB #ADSBbot