Boarding on the Lake Shore ends at 9:25, 5 minutes before departure just like any other train boarding in Union Station. I have boarded the train at 9:20 and it has not been a problem (primarily connecting to the train to get home to South Bend after a flight into O'Hare or Midway).
Oops, I apologize. I was thinking it departed at 9 pm. Arriving at 9 pm to 9:15 and then boarding is definitely possible.
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