“Where do eggs go on vacation?”/“New Yolk City.”

A popular silly riddle is told about New York:
 
Q: Where do eggs go on vacation?
A: New Yolk City.
 
The “Where do eggs go on vacation?” joke has been cited in print since at least 2009. “Where do cows go on vacation?”/“Moo York!” is a similar joke.
 
There are several other “New Yolk City” egg puns. “What is the egg capital of the world?”/“New Yolk City” was cited in 1987. “What do you call a city of 20 million eggs?”/“New Yolk City!” was cited in 2004 and 2009.
     
 
Google Books
Giggles, Gags & Groaners
By Joseph Rosenbloom
New York, NY: Sterling Publishing Company, Inc.
1987
Pg. 61:
What is the egg capital of the world?
New Yolk City.
 
Google Books
Dude, Got Another Joke?
By Bob Phillips
Eugene, OR: Harvest House Publishers
2002
Pg. 163:
Reba: What is the egg capital of the world?
Rene: I’m in the dark.
Reba: New Yolk City.
   
Google Books
The Egg Book
By Jean Paré
Edmonton: Company’s Coming Pub.
2004
Pg. 128:
If you have twenty million eggs, you have New Yolk City.
 
Google Books
July 2009, Boys’ Life, “Think & Grin,” pg. 52, col. 1:
Elaine: Where do eggs go on vacation?
Peter: I don’t know.
Elaine: New Yolk City!
Luke Drewel, Oglesby, Ill.
 
The Good Flea
Monday, August 17, 2009
Funny Bone Monday
(...)
Question: What do you call a city of 20 million eggs?
Answer: New Yolk City!
 
Twitter
Dustin Belt
‏@dbeltwrites
What’s an eggs favorite place to visit? New yolk City! #imadethatup
10:39 AM - 22 Nov 2010
 
Twitter
dar
‏@sdkdaria
what’s an egg’s favorite place to visit?
new YOLK city
5:47 PM - 2 Mar 2015
 
MyTownTutors
Summer Jokes: Top Summer Jokes
Posted on June 1, 2015 by mmolloy
(...)
61. Where do eggs go on summer vacation?… New Yolk City!