The commuter rail agency also plans to add service on most of its lines.
The rally will be held at 11 a.m. in Hutchinson Field in Grant Park, following a parade from the United Center. The parade route is to be released Thursday.
Service and schedule changes for Metra will be detailed online at www.metrarail.com.
Metra advised riders in a press release Wednesday to expect crowded trains during the morning and evening rushes on Friday. It also said that trains might leave early if they fill up and riders therefore should consider arriving at stations earlier than usual.
The $5 unlimited ride ticket for Friday will be available from all ticket agents, but will not be available from ticket vending machines. Metra encouraged riders to buy their special $5 passes in advance.