Dharavi exists since the 1700s when Mumbai was still an archipelago of seven islands under the colonial rule of the Portuguese followed by the British. Today its official population is approximately 3 lakhs (0.3 million) and the unofficial population is estimated to be 7-8 lakhs (0.7-0.8 million) The density per sq km is between 3,00,000-3,50,000people/sq km. Average density of Mumbai is 28,000people/sq km. Average Density of New York city is 10,640people/sq km. There are approximately 60,000 housing units spread across its 575 acres, land barely two thirds of Central Park in Manhattan, New York. Its annual turnover of the informal sector is estimated to be around USD 600 million- USD 1 billion.