The rally will take place at City Hall and feature free giveaways.
"Tomorrow we are gathering together in support of our home-town Orioles," Rawlings-Blake said in a statement. "This weekend, Camden Yards was packed with Oriole fans who cheered through the cold and the rain. We are going to send a message up I-95 that Baltimore is still cheering for them, and is excited to watch them beat the Yankees on their own turf."
The mayor is inviting "Orioles fans, downtown workers and city employees to rally for the O's!" an event flier says. "Wear orange and bring your baseball spirit to cheer the Baltimore Orioles!"
Three weeks ago, the mayor ordered City Hall's lights turned orange.
The Orioles are tied 1-1 with the New York Yankees in the American League Division Series. It's the first time Baltimore has made major league baseball's playoffs in since 1997.
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