The islands come together: The Hornby Vellard reclamation project

The British East India Company used the strategically situated islands to foster trade with the subcontinent. A key measure they took to enhance commerce was to promote immigration by assuring religious freedom, liberty of trade, and freedom to build in the developing area. These measures came to change the demographics once again, as they attracted not only merchants, but also individuals seeking freedom from religious persecution and many others attracted by the booming developing area, including Banias from Goa as well as Parsis, Bohras, Jews and Gujaratis from Gujarat, and Arab traders from the Gulf and Red Sea encouraged by the offer of free passage.

With the growing expansion of the operations of the East India Company and their pro-immigration measures, the population of Bombay rapidly increased from 10,000 in 1661 to 60,000 by 1675. This increasing prosperity incited the British to start a series of land reclamations and large-scale engineering works that would end in the unification of the seven islands.

In 1782, William Hornby, then Governor of Bombay, initiated the Hornby Vellard engineering project, which consisted of building a seawall blocking the Worli creek to prevent the low-lying areas of Bombay from being flooded at high tide. This project, finished in 1782, would give rise to the construction of a series of causeways, including the Duncan causeway in 1803 which united Sion, then in the northern part of the Parel island, to Salsette island; the Colaba causeway linking Bombay with Colaba and Little Colaba; and the Mahim causeway in 1845, which united Mahim with Bandra. The final product was the unification of the seven islands into a single landmass.