Auckland is often described as a city of urban sprawl. Currently, the Auckland City Council is debating whether a more dispersed, or more condensed city is more efficient in the face of an ever-growing population, increasing fuel costs and environmental concerns.

But is Auckland really a city of urban sprawl?

Two weeks ago, Insights published a Graph of the Week  that indicated that Auckland had a higher population density than New York, and many other large, well-known cities.

Auckland is New Zealand’s largest urban area; a super city that covers 1,890 square miles (4,895 square kilometres) and is home to over 1.5 million people. It is also New Zealand’s most dense urban area.

The Graph of the Week, using statistics provided by Demographia World Urban Areas: 9th Annual Edition, put the population density of Auckland at 6,200 people per square mile, while New York’s was 4,600 people per square mile.

However, this probably does not compute for anyone familiar with the Big Apple and the bright lights of the Manhattan city skyline. Beyond question Manhattan is more densely populated than Auckland's CBD.

Indeed, the 2010 US census put New York’s population density at 26,953 people per square mile. That’s five times denser that the statistics published by Demographia.

The difference is easily explained. The US census measures population density inside New York’s metropolitan urban limit – the formal boundaries of the bustling and chaotic City that Never Sleeps. This is an area of 303 square miles (784 square kilometres).

Demographia measures New York’s population density over a much larger area – an area of 4,406 square miles (11,411 square kilometres).   It uses techniques like satellite photos of suburban lights on a clear night to assess the extent of urban sprawl beyond the metropolitan limit.

In short, there is no inconsistency between the two measures of population density. Which one is the more appropriate depends on the purpose.

If the purpose is to assess the extent of urban sprawl, it does not make sense to stop at the city limit if this is not where the sprawl ends. Using photos of the lit-up areas at night to gauge where the built-up areas end makes sense.

That is why the Graph of the Week focused on Demographia’s measure of density. It shows that Auckland’s population density must be greater in the outskirts of Auckland than in the outskirts of New York’s metropolitan limit.