U.S. currency has portraits of presidents (and statesmen) on paper money and coins. The one-dollar bill has George Washington; the two-dollar bill has Thomas Jefferson; the five-dollar bill has Abraham Lincoln; the ten-dollar bill has Alexander Hamilton; the twenty-dollar bill has Andrew Jackson; the fifty-dollar bill has Ulysses S. Grant; and the one hundred-dollar bill has Benjamin Franklin. Only Alexander Hamilton and Benjamin Franklin (two founding fathers) were never president.
   
The slang “dead presidents” for paper money has been cited in print since at least the 1944, when it was defined in Dan Burley’s Original Handbook of Harlem Jive.
 
 
Wikipedia: List of U.S. Presidents on U.S. currency
This is a complete list of United States Presidents by currency appearances. The President of the United States has appeared on official banknotes, coins for circulation and commemorative coins in the United States, the Confederate States of America, the Philippine Islands, the Commonwealth of the Philippines and around the world.
 
(Oxford English Dictionary)
dead president n.  [with allusion to the portraits of statesmen found on U.S. banknotes] U.S. slang a U.S. banknote; chiefly in pl.
1944 D. Burley Orig. Handbk. Harlem Jive 136   *Dead President, a dollar bill, paper money of any denomination.
1970 L. Rainwater Behind Ghetto Walls 330,  I want me a 1965 Cadillac and some dead presidents (money) in my pocket.
 
Google Books
Cassell’s Dictionary of Slang
By Jonathon Green
Cassell
2006
Pg. 389:
dead president

dead man, dead one, president)
[1940s+] (US) a $1 bill; thus in pl. money
[the pictures of US presidents that are printed on the various denominations]
   
Google Books
Look South to the Polar Star
By Holger Cahill
New York, NY: Harcourt, Brace and Co.
1947
Pg. 226:
“Pigeon dropping for pictures of dead presidents.”
The tall girl looked at Mallett and turned haughtily away.
“What are you talking about?” Ailes said.
“The Jap. He’s spreading his bird lime for sucker money.”
 
29 January 1950, Lima (OH) News, “Looking at Lima,” pg. 2A, col. 1:
DICK BEHR brings this story back from a recent business trip to New York. It seems some “tired businessmen” were looking for a place to go and asked a cab driver for suggestions.
 
The cabbie replied:
 
“Mister, in this town you can find anything you want. All it takes is a loot of those pictures of dead Presidents to pay the bill.”
 
Google Books
23 November 1959, Life magazine, “Deejay Slang Glossary,” pg. 45, col. 3:
Dead Presidents—$20 bills with Andrew Jackson portrait, $50s with Ulysses Grant portrait, etc., used in payoffs.
 
Google Books
Behind Ghetto Walls:
Black families in a federal slum
By Lee Rainwater
Chicago, IL: Aldine Pub. Co.
1970
Pg. 419:
John: It’s only two things I like. I want me a 1965 Cadillac and some dead presidents (money) in my pocket.