S. Dillon Ripley Center located in the National Mall in Washington, D.C. DOES NOT have a dedicated nursing mothers room, but moms can use the following:
One mom wrote:
Nursing: There are lots of benches, not incredibly comfortable but they work fine. Unless there is Discovery Theater going on the area is pretty quiet, a particularly good spot is the hallway leading down towards the African Art Museum.
Changing Table: In the hallway that leads to the African Art museum there are a number of tables that are the perfect height for changing on! I didn’t see an “official” changing table in the one bathroom I went into, but there are plenty of benches to use.