Willie Morris (1934-1999) was born in Jackson, Mississippi, and became editor of Harper’s magazine in 1967. An article in the June 1967 Harper’s was titled “A provincial in New York: Living in the big cave.” Morris dubbed New York City as the “Big Cave” several times in his memoir North Toward Home (1967).
 
The New York City nickname of “Big Cave” has been used by almost no one besides Willie Morris, but this 1967 nickname—several years before “Big Apple” was rediscovered by the New York Convention and Visitors Bureau in 1970-71—is worthy of note.
 
   
Wikipedia: Willie Morris
William Weaks “Willie” Morris (November 29, 1934 — August 2, 1999), was an American writer and editor born in Jackson, Mississippi, though his family later moved to Yazoo City, Mississippi, which he immortalized in his works of prose. Morris’ trademark was his lyrical prose style and reflections on the American South, particularly the Mississippi Delta. In 1967 he became the youngest editor of Harper’s Magazine. He wrote several works of fiction and non-fiction, including his seminal book North Toward Home, as well as My Dog Skip.
 
Harper’s magazine
ARTICLE — From the June 1967 issue
A provincial in New York
Living in the big cave [(part I)]
By Willie Morris
 
Google Books
North Toward Home
By Willie Morris
Boston, MA: Houghton Mifflin
1967
Pg. 318:
OUR LITERATURE is filled with young people like myself who came from the provinces to the Big Cave, seeking involvement in what one always thought from the outside was a world of incomparable wonder, hoping for some vague kind of literary “fulfillment.”
 
Google News Archive
22 October 1967, Milwaukee (WI) Journal, “From Yazoo to Manhattan’s ‘Cave”: An American Journey Is Retraced” by William C. Haygood, pt. 5, pg. 4, col. 8:
Morris’ reactions to New York, which he calls The Big Cave, are shrewd and frequently hilarious.
(Review of the book North Toward Home—ed.)
   
Garden & Gun
The Southern Invasion of NYC
Michael Turek
BY JESSICA MISCHNER - NEW YORK CITY - APRIL/MAY 2010
Southern culture is hot in the Big Apple. Here’s how and where to find it
Famous Southern story: In the spring of 1963, a young Mississippian named Willie Morris hops a Greyhound bus bound for New York City. In short order, he goes on to become the youngest editor in chief ever to preside over Harper’s magazine, a star of Manhattan’s literary scene, and close personal friends with the likes of William Styron and Frank Sinatra. But for all his success, and much as he loves New York, Morris never feels comfortable in the place he refers to as the “Big Cave.” He longs for his hometown of Yazoo City and the “lush hills” of his boyhood. Describing this internal struggle in his best-selling 1967 memoir, North Toward Home, he says, “The massive office buildings where people worked, the jostling for position in the elevators…, the windows opening out onto other office buildings equally massive and impersonal—all this was part of a way of living unknown to me, uprooted from the earth and its sources.”
 
Google Books
Conversations with Willie Morris
Peggy Whitman Prenshaw, General Editor
Jackson, MS: University Press of Mississippi
2000
Pg. 8:
Harper’s Willie Morris
Richard Cohen / 1969
From Women’s Wear Daily: The Retailer’s Daily Newspaper, 19 August 1969, 38-39.
Pg. 9:
Morris descends. He jostles his way through the crowds becoming part of the myth of the small-town boy come to the Big Apple (the Big Cave, he calls it) to hack out his niche.
 
The Huffington Post
He Ain’t Wrong, He’s Just Different
By Dan Rather
Posted: 12/10/2012 12:15 pm
(...)
New York, of course, is too sophisticated for that — which may be one reason real honky-tonk music in general and the Texas genre in particular are so seldom performed up here in what the late Willie Morris dubbed “The Big Cave” (New York City).