The city's economy relies heavily on retail and services. The largest center of commercial activity is South Coast Plaza, a shopping center noted for its architecture and size. The volume of sales generated by South Coast Plaza, on the strength of its more than 270 stores, places it among the highest volume regional shopping centers in the nation. It generates more than $1 billion per year in revenue. South Coast Metro is a commercial, cultural, and residential district surrounding South Coast Plaza in northern Costa Mesa and southern Santa Ana, itself part of the South Coast Plaza–John Wayne Airport edge city.