Quietly, somberly, people stepped up the stairs of an old bus here on Tuesday and tried to peer back into the life of Rosa Parks, a woman whose seemingly simple trip on the bus five decades ago had, they said, changed their own.

"She showed me that maybe you can change the world, maybe I can change the world," said Tyrone Ashe, one in a stream of visitors to the Henry Ford Museum, where officials say they have on display the very city bus, No. 2857 from Montgomery, Ala., in which Mrs. Parks once refused to give up her seat.

As memorials were planned in her honor in several cities, people around the country reflected on Mrs. Parks's legacy, the oldest among them recalling their own days of entering separate doors and bathrooms and restaurants, the youngest speaking more fuzzily of a woman whose name they had read in their history texts.

President Bush described her as "one of the most inspiring women" of the 20th century, one who would always carry a "special place in American history."

Representative John Conyers Jr., the Michigan Democrat whose office employed Mrs. Parks for two decades, called the modest and unassuming woman who once worked as a seamstress a giant.

"There are very few people who can say their actions and conduct changed the face of the nation, and Rosa Parks is one of those individuals," Mr. Conyers said.

The Rev. Al Sharpton called for flags to be flown at half-staff.