Green’s Dictionary of Slang

1. affluent suburbs, typified by wealth and a love of horses, when found outside any city; the inhabitants can be black or white; thus milk/mink and manure (belt), as adj.

1960		Jazz Rev. III 36/1: Westbury lies at the heart of the North Shore’s ‘mink and manure’ belt and its principle thoroughfare [is] named for one of the pioneer millionaires.
1977		J. Waring Hot Air 12: The Mink and Manure set of Johannesburg might seem a trifle nouveau riche to the Constantia and Bishopscourt dwellers.
1984		J.T. MacFadyen Gaining Ground 130: Sudbury, Massachusetts, twenty miles north of Boston — a wealthy mink-and-manure-belt suburb.
1985		Frontline Sept. 23: Our car eventually hits the clean smelling mink and manure black area called Diepkloof Extension. It is like another world [DSAE].
1998		T. Harpur Prayer 48: It runs over a corner of the greater Toronto area‘s ‘mink and manure belt’.
2008		Mail and Guardian (Johannesburg) 15 Feb. 🌐 Many of the the early residents of these areas are snooty mink-and-manure types.
2011		Mail and Guardian (Johannesburg) 27 May 🌐 His outfit of tight jeans, cowboy boots with spurs, and a white stetson [...] should have signalled that this was a man whose manners would be outside what would be considered polite [...] among the mink-and-manure set.

2. (S.Afr.) the affluent rural areas that lie between Pretoria and Johannesburg.

1981		Signature May 9: Often I am asked how Cape Town so far from the mink and manure belt draws the cream of South African riding talent to the [...] International Show [DSAE].
1991		Bedside Guardian 40 86: One of the country’s oldest townships, Alex sprawls across about one square mile of hillside, abutting the ‘mink and manure belt’ of Johannesburg’s northern.
1998		C. Mitchell Passport S. Afr. 79: Among wealthy whites in the so-called Milk and Manure belt of Johannesburg’s northern suburbs, grand displays of [...] imported haute couture were once the rage.
2001		S. Conn Distances 31: Smack in the mink and manure belt; in its post-Raj way, more English than the English.