Zhengzhou is one of the fastest-growing cities in central China, its population climbing from 800,000 to 6.6 million since 1980. Much of its growth has come a manufacturing boom; in fact, it contains the largest smartphone production site in the world and is also known as "iPhone City". Zhengzhou’s metropolitan area covers 1,649 square miles (4,271 square kilometers) along the southern bank of the Yellow River. 34.764000°, 113.684000° Source imagery: Google Timelapse / Planet | Daily Overview