For more information on NY City's annual Halloween event in Greenwich Village (in its 33rd year with 2 million participants and $60 million in revenue for the city):
http://www.halloween-nyc.com/fact_sheet.php

http://en.wikipedia.org/wiki/New_York's_Village_Hal

loween_Parade

For background information on Halloween in West Hollywood founded in 1987 that attracts more than 500,000 revelers: http://www.socal.com/absolutenm/templates/?a=115