(Mascoutah, IL) — The number of cities served from the under-used MidAmerica Airport has grown by 33-percent … to four. Allegiant Air, the only airline flying from the St. Clair County airport, Thursday announced twice-weekly flights to Fort Myers, Florida, beginning in mid-February. Allegiant already operates a limited schedule of flights to Orlando and St. Petersburg, in addition to flights to Las Vegas, where Allegiant is based.