The Yangtze Delta or Yangtze River Delta (YRD, Chinese: 长江三角洲 or simply 长三角), once known as the Shanghai Economic Zone, is a megalopolis generally comprising the Wu-speaking areas of Shanghai, southern Jiangsu, northern Zhejiang, southern Anhui. The area lies in the heart of the Jiangnan region (literally, "south of the Yangtze"), where the Yangtze drains into the East China Sea. Historically the fertile delta fed much of China’s population, and cities and commerce flourished. Today, it is one of China’s most important metropolitan area and is home to China’s financial center, tourist destination and hub for manufacture ranging from textile to car-making. In 2021, the Yangtze Delta had a GDP of approximately US$4.3 trillion, about the same size as Japan.
The urban build-up in the area has given rise to what may be the largest concentration of adjacent metropolitan areas in the world. It covers an area of around 350,000 square kilometres (140,000 sq mi) and is home to over 240 million people. With about a sixth of China's population and a fourth of the country's GDP, the YRD is one of the fastest growing and richest regions in East Asia.