Chicago to Milwaukee

I%26#39;m going to be in Chicago for a long weekend next week and was thinking of taking a train up to Milwaukee for a day.

Is it possible to buy train tickets just before the trains go? I don%26#39;t know how many hours I will spend in Milwaukee but would like the flexibility to catch a train there early and then come back when I feel I have seen the city (wether thats early or late afternoon).

Is it possible to buy an open day return ticket?

Can someone advise me please?

Chicago to Milwaukee

It is not possible to buy an open ended ticket. Unless I%26#39;m underestimating the crowds on the Chicago-Milwaukee Amtrak trains, you should be able to buy a ticket at Union Station prior to boarding. However, you may want to call 1-800-USA-RAIL earlier in the day to check the current status of the trains for that day.