Marion Barry arrived in Washington in 1965 as a young civil rights activist with no profile but eager to make a difference. His departure, nearly 50 years later, begins Thursday in a manner befitting a civic icon who left an indelible mark on the city he adopted.

The casket of the four-term D.C. mayor, who died Nov. 23 at 78, will be taken to the John A. Wilson Building in the morning for a brief ceremony, after which Barry’s remains will lie in repose through the night.

The casket is expected to be visited at 8:30 a.m. Thursday by Mayor Vincent C. Gray (D) and D.C. Council members past and present. The public is invited to pay its respects there from 9 a.m. till midnight Thursday, as well as from 6 to 9 a.m. Friday

Barry’s farewell could cause some disruption to the morning commute, with the city announcing intermittent street closures expected in front of the Wilson Building, in the 1300 block of Pennsylvania Avenue NW, as the casket and family members arrive.

Some details of the “homegoing” events, including the route of a funeral motorcade through the city planned for Friday, remained in flux Wednesday.

Key locations for Barry memorial (The Washington Post)

The events are being planned in accordance with Barry’s wishes by his widow, Cora Masters Barry, and his son, Christopher, in conjunction with city officials. The closely guarded planning has generated a good deal of speculation — including talk of a horse-drawn cortege — and some confusion.

At some point Wednesday, reports circulated that Pennsylvania Avenue NW between 12th and 14th streets would be closed throughout the day Thursday and into Friday, potentially causing a greater disruption, particularly with the lighting of the nearby National Christmas Tree set for Thursday evening. Those plans, however, were scaled back.

The disruptions Friday could be more significant as Barry’s casket is taken from the Wilson Building in the morning to a church in Southeast Washington for a public viewing and community memorial service in Ward 8, which Barry represented on the council for 12 years.

City officials and Barry family representatives were unable to give details of the motorcade route, which was originally expected to wend through all eight of the city’s electoral wards. People familiar with the planning but not authorized to publicly comment said the route had not yet been finalized Wednesday evening.

D.C. Council members were told Tuesday morning, however, that the plans had been scaled back, with the procession expected to take a more direct route to the Temple of Praise, at 700 Southern Ave. SE, on the city’s southeastern border.

The public viewing there is scheduled from 1 to 6 p.m. Friday, with a memorial service to follow at 7 p.m.

An even grander farewell is scheduled for Saturday at the Walter E. Washington Convention Center, which will be set up to accommodate thousands of people.

Greg O’Dell, the center’s chief executive, said the halls reserved for the event can hold as many as 14,000. The proceedings are also expected to be televised, he said, although details of those arrangements were not available late Wednesday.

Another viewing is scheduled for the convention center from 7 to 10 a.m., to be followed at 11 a.m. by a four-hour event — “The D.C. Celebration of the Journey of Mayor for Life: Marion Barry Jr.” — expected to feature a broad array of musicians, ministers and other speakers.

The District government is bearing most of the cost of Barry’s farewell, and some private fundraising is underway to supplement the public spending. A number of businesses and community groups have been approached to donate to a “Marion Barry Homegoing Fund,” with at least one group being told that the money was needed to print up as many as 50,000 souvenir programs for the Saturday service.

LaToya Foster, a spokeswoman for the Barry family, said she did not have information on the private fundraising.

More street closures are expected around the convention center Saturday, and further traffic disruptions are expected as Barry’s casket is taken to his final resting place, at Congressional Cemetery on the eastern edge of Capitol Hill. The burial will be private.

Aaron C. Davis contributed to this report.