Godspell/WMG

In The Movie, New York City becomes empty upon Jesus's baptism.
There are still people in Central Park when the cast is running to Bethesda Fountain. There is a man in a rowboat in the lake in the widescreen version of the film, behind Jerry (the one with the mustache) as he splashes back and forth with John the Baptist. So while it's not implicitly stated when New York empties out, there's no one else after that.

Everyone else in New York City was at a big party during the movie.
That's why they all come around the corner from the same block at the end.