William Whyte was a sociologist whose studies came to include public spaces in American cities, especially plazas and parks here in New York City. Most of his work isn’t directly applicable to the rallies and marches we organize, but the combination of observation and attempting to predict which interventions will improve people’s experience does have some familiar echoes.
Whyte’s research is documented in a book and film, which is preserved in several different versions shown in the years of the late 1970s and early 1980s. One version of the film is on Daily Motion, and the book is at the Internet Archive (free account required to read).
You can find a capsule biography of Whyte at Wikipedia.