I used to live just 4 blocks from 15th & Broadway there.... that would have gotten me out to walk over.

Here in Maryland, we have an annual "remember Veterans" with the Rolling Thunder rally.
   Several years ago, I got caught in it and my way to a shop was blocked for over an hour, as they were going just a short distance from where I was going.
I'm not sure that I agree that one continuous line that ties things up for hours is more 'patriotic' or 'meaningful' than just assembling at the meeting place...but no doubt it's hard to argue with a few thousand bikers...who would likely do it without a permit and make things even more chaotic.