Don't you need a permit?
The very short answer is no. However, the government can place some restrictions. So if you want to use loudspeakers, block traffic etc. you do need a permit and it most certainly varies by jurisdiction.
There is obviously many details involved. What if the police barricaded a street, can I go off the sidewalk onto the roadway? I honestly don't know.
My main point was that generally speaking it's not up to the police to grant permission to assemble. It's a first amendment right.
