• An urban area that is experiencing growth is the city of Kolkata (formally known as Calcutta) located in the north east of the country. Kolkata used to be the capital city of India until 1911 and has seen rapid growth in its size and challenges throughout its history. Rapid urban growth saw constant problems at the bridging point of the River Hooghly where there was only one road bridge.
• However, the wealth and the growth of the affluent areas is in sharp contrast with the poverty of the millions of immigrants who live in make-shift shanty towns called bustees.
• Many refugees date from the partition of India in 1947 while others moved into the city after the violent separation from Bangladesh in 1971. Many other refugees fled to this city from religious or ethnic problems that occur in various parts of the country.

The Kolkata Municipal Corporation (KMC):

• The central city of Calcutta, now called Kolkata, remains one of the densest on earth. Its population density is 63,000 per square mile (24,000 per square kilometer) is nearly the same density as in Manhattan or the Ville de Paris.
• More accurately, it resembles the entire urban area densities of Mumbai and Hong Kong. The expanding suburbs of Kolkata have a population density of 25,000 per square mile (9,000 per square kilometer). The next edition of Demographia World Urban Areas (due out in the spring) will estimate the population density of the Kolkata urban area at 30,000 per square mile (12,000 per square kilometer).
• Kolkata's spreading urbanization, however, has been going on for at least a half century. Since the 1951 Census, the central city of Kolkata has accounted for only 19% of the urban area population growth. The central city has added nearly 1,800,000 people while the suburbs have added approximately 7,650,000 (Figure 1).

• Over the past two decades, the central city's growth has been minimal, adding 87,000 people from 1991 to 2011, while the suburbs added more than 3 million new residents. This intensifies the pattern of the last half-century where most growth clustered close to the city core.
• Between 1901 and 1951, 59% of the growth in the Kolkata urban area was in the central city (Kolkata lost the British capital to Delhi in 1911).

Slower Growth in the Urban Area:

• Kolkata is an unusually shaped urban area, nearly 50 miles (80 kilometers) long and stretched along the Hooghly River, one of the many mouths of the Ganges. Dhaka, the megacity capital of Bangladesh used to be on a mouth, until the river's course changed. The urban area averages little more than 10 miles (16 kilometers) in width.
• The municipality of Kolkata is in the south, on the east bank of the Hooghly, with most of the suburbs to the north or just across the river.
• Like a number of major urban areas around the world, Kolkata has seen its population growth slow markedly. The peak population growth decade was the 1930s, when there was an increase of 69%. Growth dropped to 29% during the 1940s but continued at 20% or more until 2001.
• However, between 2001 and 2011, the urban area growth rate dropped to 7%, as the area added only 900,000 new residents. Despite its earlier, smaller size, the Kolkata urban area had not added this few people since the 1921 to 1931 decade.
• In reality, Kolkata is getting less dense by the day. The results of the 2011 Census of India showed that every new resident of the Kolkata urban area was added in the suburbs (Note 1).
• Yes, the central city of Kolkata remains very dense but its population fell from 4,573,000 people in 2001 to 4,487,000 people in 2011. At the same time, the population of suburban Kolkata grew by nearly 1,000,000 people, and accounted for 110% of the population growth.
• Kolkata, Los Angeles and China: It also may seem strange that despite its huge typically third world growth since 1951, the Kolkata urban area grew at a rate similar to that of the Los Angeles urban area (Note 2). Los Angeles was larger from the 1960s to 1990, while Kolkata was larger in the 1950s and has been larger the last two decades (Figure 2).
• Still, Kolkata's growth has fallen to high income world rates. Other Asian megacities (over ten million) including Delhi, Shanghai, Beijing, Mumbai, Shenzhen, Manila, Jakarta, Dhaka and Guangzhou) have all experienced much faster growth over the past decade (Note 2). Shanghai and Beijing combined added nearly the same number of people as live in Kolkata.

Hyper-Densities:

• Nonetheless, Kolkata continues to have some of the highest densities in the world. In 2001, one third of the central city population (1.49 million) live in slums and shantytowns (photo).
• They are crammed into just 2 square miles (5 square miles). This would be like all the population of the San Fernando Valley living within a radius 0.6 miles (1 kilometer) of Los Angeles City Hall or all the population of the city of Dallas in the space covered by the passenger terminals at Dallas-Fort Worth International Airport.
• This is more than 725,000 people per square mile (280,000 per square kilometer), and would nearly equal the "efficient density" definition that the Sierra Club wisely discarded. It can only be hoped that when the 2011 Census slum data is available, it will show that all of the city of Kolkata's population loss will have been from the slums.
• Kolkata, like that of other large urban areas around the world described in The Evolving Urban Form series, shows that, given a chance, people reveal their preferences by moving to more space, to construct a better life for themselves and their households.