Milwaukee is served by many major airlines flying into Mitchell Airport, and by Amtrak. The airport is located on the south side of the city, about a 15 minute cab ride from downtown; bus service from the airport to downtown is also available. The Milwaukee downtown Amtrak station is two blocks from the conference hotel.
If you are attending the pre-conference workshop at the Newberry Library in Chicago, you could fly into O’Hare, and then take Amtrak to Milwaukee for the conference. There is also a direct coach service between O’Hare and downtown Milwaukee, which operates hourly and does not require advance reservations.