The Easter Day Parade of fashion started in the 1880s. Easter, being the holiest day of Christianity, required even the least devout to attend services and look their best. Everyone got a new set of clothes, and of course, wanted to show them off.
The Easter Parade started as an after-church event that allowed Catholics and Protestants to compete in style and be seen fashionably. Although the current parade is limited - at least by police barriers - to 49th Street, the original parade probably extended down to 29th Street, the location of the Marble Collegiate Church (Dutch Reform).
The church parishioners involved in the early parades were from, of course, St. Patrick's Cathedral (50th-51st Streets), St. Thomas's Episcopal (53rd St.), Fifth Avenue Presbyterian Church (55th St.), and most likely the "off-Fifth Avenue" churches, like St. Bartholomew's Episcopal on Park Avenue and 50th.
At the time the Easter Parade began, these churches were surrounded by the mansions of the New York elite and robber barrons. St. Thomas Episcopal was the church of the Astors and Vanderbilts. Fifth Avenue Presbyterian Church was Carnegie's church.
The modern-day parade has parameters running from 49th Street to 57th Street during the hours 10a - 4p. Fifth Avenue is blocked off so although it is crowded it isn't impassable. Everyone is encouraged to "dress up" (meaning, at least wear some kind of gaudy hat). There are a lot of really inventive hats, even on pets.
I took part in the Easter Parade once with a friend. I didn't make much of an effort - I wore my dad's golf hat - because I really just wanted to watch. My friend, who worked in fashion, didn't wear a hat at all. We spent about an hour on the sidewalk near St. Patrick's Cathedral and then went to lunch.
The parade had ended by the time we finished eating and crowds of people were headed for the subway. The sidewalk was jammed and I was ambling with my friend as fast as the foot traffic in front of us would allow me. A large man behind me thought I was walking too slowly and said so a few times before he came around me huffily and accidentally knocking me about a little. My friend, who was (and continues to be) over 6 feet tall, made a rather impolite suggestion to the man. Instead of confronting my friend, the man turned around and confronted me - telling me to go back to Ohio.
"But I live in Brooklyn," I said.
More perplexed than ever, he rushed away.
At any rate, at least once in a lifetime, everyone should make a hat and attend the Easter Parade in New York or somewhere.