Employment zones in France are defined according to the daily commutes of workers. Each employment zone revolves around a major activity center, called an “employment hub,” encompassing urban and rural municipalities from which a significant portion of the working population travels to or near this hub for work. This proportion can vary depending on the local context, but is generally between 20% and 25% of the working population of the municipality in question. Metropolitan France had a total of 348 employment zones as defined by INSEE in 1996.