Economic Development Driven By Increasing Returns

One of the lessons of empirical data on economic development is that growth takes place most vigorously in very localized areas where progress has already taken hold.  Thus, places like Silicon Valley's early lead in computer technology has driven it to become a center of computer technology decades later, and New York's early lead in the securities market has led it to dominate that market centuries later.

This is not a new phenomena.  The industrial revolution in England thrived most in the rural counties that already had significant small scale industry.  This is contrary to conventional wisdom about the English industrial revolution that has been influential with economists.