William Manchester’s book, Portrait of a President: John F. Kennedy in profile (1962), includes a famous line: “‘Washington,’ John Kennedy once said lightly, ‘is a city of Southern efficiency and Northern charm.’” The joke implies that Washington, DC has it all wrong; the South is known for its charm and the North is known for its efficiency. John F. Kennedy (1917-1963) is often given credit, but the saying has been cited in print before Kennedy joined the House of Representatives in 1947.
   
Washington Senator Warren G. Magnuson (1905-1989) said in 1945:  “Washington—with its Northern charm and Southern efficiency.” Also in 1945, the father of a Congressional Medal of Honor recipient was ordered out of a Washington dining room for his improper attire. He remarked: “A remarkable city, Washington: it combines Northern charm and Southern efficiency.”
 
   
Wikipedia: Warren Magnuson
Warren Grant “Maggie” Magnuson (April 12, 1905 – May 20, 1989) was a United States Senator of the Democratic Party from Washington from 1944 until 1981. Upon leaving the Senate, he was the most senior member of the body. Magnuson also served as a member of the United States House of Representatives, representing the Washington’s 1st congressional district from 1937 to 1944.
     
2 October 1945, New Orleans (LA) Times-Picayune, “Washington Scene: Ironies of the Hotel Heave-Ho” by George Dixon, pg. 8, col. 6:
Washington, Oct. 1.—Senator Warren G. Magnuson, of the great state of Washington—the vacationist’s paradise, tourist rates on request—came through the other day with the most pithy description of the nation’s capital I have ever heard.
 
“Ah, Washington!” sighed the senator, rapturously. “Washington—with its Northern charm and Southern efficiency.”
     
19 October 1945, Casa Grande (AZ) Dispatch, pg. 8, col. 7:
“Oh, its Northern charm and Southern efficiency!”—Senator Magnuson, Wash. State, speaking of the nation’s capitol.
 
23 November 1945, Santa Rosa (NM) News, “Quotes of the Week,” pg. 4, col. 2:
“Oh, its Northern charm and Southern efficiency!”—Senator Magnuson, Wash. State, on the nation’s capital.
 
Google Books
It Happened in 1945
By Clark Kinnaird
New York, NY: Duell, Sloan & Pearce
1946
Pg. 348:
The father of a Congressional Medal of Honor winner who was in Washington at the invitation of the President, was ordered out of the dining room of a capital hotel because he wasn’t wearing a coat. A Washington columnist reported having overheard, “A remarkable city, Washington: it combines Northern charm and Southern efficiency.”
 
Google Books
The Army Wife
By Nancy Shea
New York, NY: Harper & Row
1954
Pg. 337:
A longstanding local witticism has it that Washington is “the city that runs on southern efficiency and northern charm.”
 
Google Books
Portrait of a President:
John F. Kennedy in profile
By William Manchester
Boston, MA: Little, Brown and Co.
1962
Pg. 200:
“Washington,” John Kennedy once said lightly, “is a city of Southern efficiency and Northern charm.”
 
29 May 1962, Janesville (WI) Daily Gazette, “Capitol Puts on Cultural Airs” by John Crosby, pg. 14, col. 1:
Washington has been called a city of Southern efficiency and Northern charm (most recently by President Kennedy, who attributed it to someone else) but this is rapidly becoming both untrue and unfair.