This was probably the 1967 parade featuring Dr. Martin Luther King.
I do not know who these ladies are, beyond that they are probably on the MICCO board. What is MICCO? It is the Model Inner City Community Organization an organization that was around during the period of Shaw’s urban renewal. It helped get federal funds to black middle class professionals such as architects and builders.
What I do know is that the float passed R Street NW. I suspect Rhode Island Ave is just a bit behind it. They might be heading north on 9th Street. I have the parade route somewhere, but I do not know where.