We’ve written quite a bit about agglomeration economies, as they’re one of the most important forces shaping urban life. Agglomeration economies refer to the benefits of proximity for economic and social interaction – when you’re around more people, it’s easier to meet the right person (for business or relationships!), easier to share knowledge, and easier to do things in general.
One “stylised fact” from the economic literature is that cities that are larger and better connected – i.e. denser and/or easier to get around – tend to be more productive. When it comes to economic performance, size matters. This benefits firms and workers, of course, but it is also good for consumers. For example, if you want to see a lot of rugby tests, you’re better off locating in Auckland than in Taupo, because test matches tend to go to where the people are. And if you want more restaurants and groceries, live in a denser neighbourhood.
However, economists have focused on agglomeration economies in production as they’re often easier to measure. For example, a few years ago the New Zealand economist David Maré estimated an “Auckland productivity premium” of around 50%. That means that firms located in Auckland are around 50% more productive than similar firms located in other regions. The premium was even higher for Auckland’s city centre.
In subsequent work, Maré and a collaborator, Daniel Graham, estimated that New Zealand had an “agglomeration elasticity” of around 0.065 (averaged across all industries). What this means is that places that are 10% denser tend to be around 0.65% more productive, all else equal.
But what does this mean in practice? How much does agglomeration contribute to the New Zealand economy? Is it a big deal, or not that important in the grand scheme of things?
To get a rough idea, I calculated changes in the “effective density” of jobs in Auckland over the period 2000-2015, taking into account the location of jobs within Auckland (from Stats NZ’s Business Demographics data) and the distance between job locations (calculated using GIS tools). I followed Maré and Graham’s formula for job density as a function of weighted distance to jobs in nearby areas – for the precise formula see equation 2 on page 12 of their paper.
Here’s a map showing how effective density of jobs changed over the whole period. Darker blues indicate higher percentage increases.
Almost everywhere in the Auckland urbanised area became more accessible to employment over this period – the rising tide of urban development lifted all boats. On average across the region, effective density rose by 29%. However, increases were faster around Albany and the upper North Shore, which saw rapid development, and slower in the western isthmus and west Auckland.
So things have changed quite a lot. The following chart shows that these changes happened incrementally over time. It shows the effective density of employment for the average job in Auckland. In 2000, the average job was proximate to around 71,000 other jobs. In 2015, that had risen to slightly less than 92,000 jobs.
So job density has gone up quite a lot over the last 16 years as a result of Auckland’s growth. What effect has this had on productivity?
As a point of comparison, I estimated changes in GDP per employee over the same period. (I used Stats NZ’s employment data, regional GDP statistics, and GDP price deflators for the whole country. This isn’t a perfect estimate, as I’ve excluded self-employed people and haven’t corrected for part-time employment, but it’s not miles off.) Here’s what that looks like. Over the entire period, GDP per employee has risen by approximately 14.4%. The city’s economy currently produces around $88.3 billion in output.
By comparison, Maré and Graham’s agglomeration elasticity of 0.065 implies that a 29% increase in job density is associated with a 1.7% increase in productivity (calculated using an arc elasticity formula: (92,000/71,000)^0.065-1). The true figure may be higher, as Auckland is specialised in industries that benefit more strongly from agglomeration economies.
- Roughly 11-12% of the total productivity growth in Auckland over the last 16 years is due to increased agglomeration economies
- In the absence of increased agglomeration economies from scale and density, Auckland’s economy would be around $1.4 billion smaller.
A wide range of other factors – increased skills, investment in capital goods, improved business practices, and changes to the composition of Auckland’s economy – also make important contributions to productivity growth. However, the contribution of agglomeration is significant – both in dollar terms and as a share of the city’s overall productivity growth. In the long term, those tenths of a percent add up to quite a lot. If we want a wealthier New Zealand, we need better, more productive cities.
Policymakers can do a lot to enhance – or undermine – agglomeration economies. For example:
- Policies that promote an inclusive and affordable housing market – with a choice of dwellings in accessible places – will allow more people to participate in urban labour markets. Conversely, limiting housing supply in the places where people want to live will “crowd out” agglomeration economies.
- We can’t build our way out of congestion, but we can do plenty to improve the efficiency of the transport system through better pricing of road capacity and provision of good, congestion free alternatives to let people get around even when the roads are busy.
What do you think about agglomeration economies in Auckland?