Romona Riscoe Benson, president and chief executive officer of the museum, said Parks' medal is "a rare part of history."
The medal adds "another dimension" to the exhibit, she said. "It really creates a continued understanding that this museum is committed to telling the story of the civil rights movement and bringing our history to the forefront for our visitors."
Benson and others hailed Peco for financial support for the exhibit.
The display, which opened July 3, is to run through Sept. 30. Benson said the medal would be at the museum during that period and possibly longer.
Parks, who died in 2005, is considered the key catalyst of the civil rights movement. On Dec. 1, 1955, Parks, a seamstress in Montgomery, Ala., refused to give up her bus seat to a white rider in violation of a city ordinance.
Her quiet act of defiance sparked a successful boycott of the city's bus system led by the young Rev. Dr. Martin Luther King Jr. and thus the movement that eventually ended legal racial segregation in this country.
The exhibit, by the artist Carlotta Janssen and titled Freedom Riders: Threads of a Story, features 82 mixed media portraits focused on the Montgomery bus boycott of 1955 and the 1961 Freedom Riders.
The Freedom Riders were civil rights activists who rode by bus from Washington into the South to test the U.S. Supreme Court's 1960 ruling that declared segregation in interstate bus and rail stations unconstitutional. Their buses were attacked and many of the dozens of riders were beaten by mobs and arrested in Alabama and Mississippi.
Janssen's portraits depict the police "mug shots" of the riders and their supporters, and other aspects of their lives.
Dean, who was general manager of the Marriott when it opened in 1995, recalled Parks' coming to the city for the opening at his request and posing for a photograph by the Liberty Bell.
"With that image in mind . . . it is only appropriate to put on display for the very first time the Congressional Gold Medal," Dean said.
He said he first met Parks in 1989 and got to know her well. "When she received the gold medal and all, I went everywhere with her, and she blessed me by adopting me as her godson."
Dean, who lives in Los Angeles and manages several hotels, said it was important that Philadelphia and the African American Museum be the first place for the medal to be on public display. "I love Philadelphia," he said.
Contact Vernon Clark at 215-854-5717 or firstname.lastname@example.org.