CHICAGO, Illinois, July 9 -- The National Railroad Passenger Corporation (Amtrak) issued the following news: * * * Amtrak and states impressed by positive response to new service * * * Preliminary figures from the first full month of state-sponsored Borealis trains between St. Paul and Chicago show a ridership of greater than 18,500. That is an average of about 300 passengers aboard each of the eastbound and westbound trains operated daily by Amtrak under contracts with Wisconsin, Minnesota   more