Milwaukee Mitchell International Airport: Take MCTS GreenLine toward downtown/Upper East Side: roughly 20–25 minutes to the Third Ward and downtown, about $2.75, paid by contactless card/phone or the Umo app. Route 80 is the slower downtown alternative. A taxi/rideshare is sensible only with luggage or a late arrival—roughly $30. Skip the airport shuttle unless its schedule happens to suit you; the regular bus is cheaper and direct.
Milwaukee Intermodal Station: This is the useful downtown rail arrival: Amtrak Hiawatha from Chicago Union Station takes about 1 hour 30 minutes; Borealis also links Chicago and St. Paul, while Empire Builder is the long-distance option. The station is walkable to Westown and the Third Ward, and The Hop streetcar is free for downtown connections.
Milwaukee Airport Rail Station: For Amtrak Hiawatha/Borealis passengers using MKE, take the free shuttle between the terminal and the rail station 1.6 miles away. It works well only when the train timetable aligns; otherwise use the GreenLine bus into town.
Chicago O'Hare International Airport: Use this only when the flight saving is substantial or MKE lacks your route. Wisconsin Coach’s direct airport shuttle to Milwaukee Intermodal/MKE is about $26 and avoids crossing Chicago. A cheaper rail workaround—CTA Blue Line to Chicago Union, then Amtrak Hiawatha—can work, but takes around three hours from landing with good timing and is fragile after delays.
Chicago Midway International Airport: There is no equally convenient direct rail link to Milwaukee: take the CTA Orange Line to downtown Chicago/Union Station, then Amtrak Hiawatha. Allow about three hours from landing with a clean connection. It is a reasonable fare-driven alternative, not a convenient Milwaukee airport.