I spent most of my 20s doing grassroots campaigning, with a large part of it being protest planning and organization. You generally do not need a permit to conduct protests on public property, even large ones, in the USA.
The exceptions are very specific; i.e. blocking roads may require a permit.
And fifth/sixth derivatives are crackle and pop because some physicists thought it would be funny to have it be “snap crackle and pop”