This epic is also a tale of mundane places: lunch counters, buses, motels, schoolrooms. Yet lives were sacrificed over the right to use them, one reason Room 306, with its portrayal of life interrupted, is so affecting.

Given the museum’s accomplishments and the likelihood that other institutions will follow its lead, its flaws are also worth attending to. The museum approaches its subject as an advocate — it would have to — but it is overly wary of complication. We learn little, for example, about movement schisms. There are some signs of disagreement — particularly in a few discussions of Malcolm X or the black power movement — but more detail would have illuminated Dr. King’s own evolution and shed light on debates that followed.

The museum’s advocacy can also distort: The Black Panther Party is portrayed as a victim of governmental sabotage, without a hint of what the writer Stanley Crouch described as its descent into violence to feed a “lucrative criminal enterprise.”

And it is taken for granted that early racial restrictions are analogous to later inequities and differences. In the Jim Crow gallery, for example, contemporary maps showing racial distributions in New York City, Kansas City, Memphis and Atlanta are labeled “Jim Crow Today” because they demonstrate “de facto segregation.” In addition, we read, “The high percentage of people of color in the criminal justice system can be linked to discrimination in policing — much like during the heyday of Jim Crow.” Don’t these assertions deserve more complex analysis?

Such considerations are clearly for another day. Now, the point is commemoration, accompanied by activist passion. Just before his murder, Dr. King asked that “Take My Hand, Precious Lord,” be sung at a dinner he was about to attend. It was sung at his funeral instead. We hear it as we gaze at Room 306. The song’s pleas for guidance and strength, the room’s frozen tableau and the museum’s survey of riots and mourning — all point to a project left unfinished.