Alaska became the 49th state in the United States on January 3, 1959. Alaska’s great size meant that Texas was no longer the largest state in the United States—as Texans have long liked to brag.
 
Alaskans took Texans down even further: If Alaska were to be cut in two, Texas would be the third largest state! This Alaskan “put-down” began in 1958 and is still told by many Alaskans.
 
 
Wikipedia: Alaska
Alaska is a state in the United States of America, in the northwest of the North American continent. It is the largest U.S. state by area, and the 6th wealthiest (per capita income).
 
The area that became Alaska was purchased from the Russian Empire after Congress concluded its resources could be vitally important to the nation’s future growth. The United States completed the purchase on March 30, 1867, for $7.2 million at 2 cents per acre, about 5 cents per hectare. When adjusted for inflation, the total sum paid equates to approximately $360 million in 2008 dollars.The land went through several administrative changes before becoming an organized territory on May 11, 1912 and the 49th state of the U.S. on January 3, 1959. The name “Alaska” was already introduced in the Russian colonial time, when it was only used for the peninsula and is derived from the Aleut alaxsxaq, meaning “the mainland,” or more literally, “the object towards which the action of the sea is directed.” It is also known as Alyeska, the “great land”, an Aleut word derived from the same root. 
   
Wikipedia: List of U.S. states by area
state/territory   total (mi²)    (km²)
Alaska             663,267     1,717,854
Texas             268,581       695,622
 
25 November 1958, Ames (Iowa) Daily Tribune, pg. 4, col. 4:
Charlie Caven was telling the story this week of the Texan who was visiting in Alaska. As usual he was bragging about the virtues of his state. Finally one of the Alaskans had had enough. “Pipe down,” he growled, “or we’ll cut Alaska in half and make Texas the third biggest state.”
 
22 November 1959, Long Beach (CA) Independent-Press-Telegram, pg. C4, col. 1:
One member of the Baylor party here last week for the SC game was doing a bit of boasting about you-know-what when he was squelched with “careful, fellow, or we’ll cut Alaska in half and then Texas will be the THIRD largest state.”
 
Google Books
The New Book of Knowledge
Published by Grolier
1986
Pg. 2:
One joke has it that a Texan and an Alaskan were having a heated argument. Suddenly the Alaskan said, “You better watch out or we’ll cut Alaska in half and make Texas the third biggest state!”
 
Feld Thoughts 
July 29, 2008 12:27 AM
Why I Spend A Month A Year in Homer, Alaska
I wish it were as simple as “the weather.”  After 27 days in a row of rain (ok - we had sun for part of two days), the sun finally came out today.
 
I’ve been coming up to Alaska in the summer for about 15 years.  Amy grew up here and after we started going out together it seemed like a trip to her home state was in order.  I grew up in Texas, so after putting up with the “if you cut Alaska in half Texas would become the third largest state” jokes, I took a trip and immediately fell in love with the place. 
     
Anchorage (AK) Daily News
Alaska deserves better than corrupt politics and Big Oil
ELISE PATKOTAK
COMMENT
Published: August 19th, 2008 10:57 PM
(...)
To update the old saying that if you cut Alaska in half, Texas would become the third largest state in the union, she suggested if you cut Alaska in half, New Jersey would become the third most corrupt state in the union. Ouch!