This picture in USA Today puts today's One Nation Rally in perspective if you know what you are looking at. The picture below is taken across the reflecting pool from in front of the Lincoln Memorial looking back towards the east/south/east.
You will notice beyond the trees there is a grassy area in the background. That grassy area beyond the trees was the overflow area for the 8-28 ralley, This picture (below) was taken at the far end of that overflow area looking back towards the Lincoln Memorial which you can see the very top of in distance.
So all that green area you see in the first photo was filled with people on 8-28. You can see what I am saying in this photo taken on 8-28
The entire area to the left of the trees on the left side of the picture above was empty today but filled to the max on 8-28. There are several other indications that today's lefty ralley was far smaller than 8-28, but this is pretty conclusive.