What led to

When Bombay became the capital of the Bombay Presidency in 1819, the city quickly expanded.

(2) With the growth of trade in cotton and opium a large number of traders and bankers, artisans and shopkeepers came to settle in Bombay.

(3) The establishment of textile mills led to a fresh intake of the population. People migrated from Ratnagiri and far away places.

(4) When Bombay became the hub of Indian films, many new people — singers, actors, poets, play writers migrated to the city.

(5) Bombay was at the junction head of two major railways. This encouraged a higher scale of migration into the city.