Periphery (France)


A periphery, is an INSEE statistical area designating a commuter belt around an urban unit. Together these complete the INSEE urban area statistical area.
Based on France's commune system, a commune is considered part of a couronne when
  1. it is not densely constructed enough or is too isolated to be part of any unité urbaine, and
  2. at least 40% of its population commutes to workplaces in a unité urbaine or pôle urbain, or to another commune connected to a unité urbaine through the same criteria.