Manchester, England, is seen as the first industrial city because it was the first city to be dominated by industrial factories. The weaving of cloth was the first huge industry and Manchester was the center of that industry. Because it was the center of the first major industry, it is seen as the world's first industrial city.
By the early 1820s, Manchester had come to be dominated by the cotton industry. It had also come to be the main center of that industry. Its level of industrialization grew rapidly. In 1818, the Manchester area had 14 factories with about 2,000 powered looms for making cloth. By 1821, the city had 32 factories with 5,732 powered looms (these statistics are found here). This was more than half of the powered looms in all of England.