Victor airways in USA
 

The FAA Historical Chronology 1926-1996 states "Jun 1, 1952: Forty-five thousand miles of very-high-frequency (omnirange) airways, referred to as "Victor" airways, were put in operation. Like the then existing 70,000 miles of Federally maintained low-frequency airways, the "Victor" routes were 10 statute miles in width."

So Victor airways originally had a width of 10 sm (8.68 nm). Today, the standard width is 8nm.

Does anyone know when the change in width occurred?