Had she lived a few more weeks, Rosa Parks could have seen the federal building near her home in Detroit renamed today to mark the 50th anniversary of her refusal to surrender a bus seat to a white man.

Scattered ceremonies across the Washington region will honor Parks's memory on today's anniversary, which falls just 38 days after her death Oct. 24 at age 92.

A consortium of antiwar, labor and civil rights groups plans marches and rallies in Washington and Baltimore as part of a national day of absences and strikes patterned after her protest. Montgomery County Executive Douglas M. Duncan announced that permanent plaques dedicated to Parks would be installed in all Ride On transit buses. And at the National Archives, the exhibit "Mother of the Civil Rights Movement" will mark the anniversary until Dec. 15.

Dozens of urban bus systems across the country will pay tribute to Parks, according to the American Public Transportation Association. Six thousand buses in New York's Metropolitan Transportation Authority fleet will dedicate a front passenger seat and leave their headlights on in her honor. A bus system in Lake County, Ohio, will offer a reenactment of her civil disobedience. In the District, Metro will dedicate a 1957 bus at a noon ceremony in front of the agency's headquarters.

Several D.C. groups plan an 8:30 a.m. march from Franklin Square to the White House for an 11:30 a.m. picket and rally around several causes -- poverty, racism, the war in Iraq and the victims of Hurricane Katrina. A similar event is planned in downtown Baltimore.

Detroit, Parks's final home, will host an array of events, capped by an afternoon renaming ceremony of the Rosa Parks Federal Building. A spokesman for Rep. Carolyn Cheeks Kilpatrick (D-Mich.), who proposed the name, said the chorus of tribute might have overwhelmed the famously humble Parks.

"She never sought the limelight," said Cliff Russell, the spokesman. "Just a very humble, unassuming spirit, but certainly someone who had strong principles, strong convictions and a spirit of defiance against injustice."