I was there, too.
When our buses arrived, we were dropped off at the western end of Freedom Plaza around 9. The crowd continued to grow and the march started early because they said we were overflowing the area.
We thought we would be bringing up the rear but as we moved along it was obvious that there were a LOT of people, and i mean A LOT!! behind us.
The coolest thing, often there would be a roar of sound (people cheering) rolling up behind us like a wave, engulfing us as we joined in, and then continued on. I have NEVER heard anything like it!
I heard the rolling sounds too. It gives me chills even now, thinking about it and hearing it again in my head. It was an awesome sound, an awesome experience and I’m so glad that I was part of this historic event.