3

# 1 Introduction: Looking Beyond Urban Aggregates

A decade ago, the world reached an important “tipping point”—half its population became urban. By 2030, almost 60% of the world will live in urban areas. About 90% of the world’s urbanization in the next decades is expected to take place in the urban areas of Asia and Africa (United Nations, 2015). Not only is this part of the world urbanizing, it has been doing so at an extraordinarily rapid pace. While it took Industrial Europe 110 years (1800‐1910) to increase its rate of urbanization from 15 to 40 percent, Asia and Africa did so in only 50 years (1960‐2010), or twice as fast (Jedwab, Christiaensen, Gindelsky, 2017).

Many issues in urbanization are hotly debated. These include, for example:

- The association, and two‐way causal relation, between urbanization and growth. The association is an essential aspect of classical theories of development (Lewis, 1954).

- Asia versus Africa. Is African urbanization “different”? (Henderson, Roberts, and Storeygard, 2013; Gollin, Jedwab, and Vollrath, 2016).

- The association between unemployment, poverty reduction and urbanization. (The vast literature emanating from Todaro, 1969, and Harris and Todaro, 1970.)

- Urbanization and formalization (e.g. Ghani and Kanbur, 2014).

- Is urbanization delivering the benefits of agglomeration? (Duranton, 2015)

However, all of the above is in an aggregative perspective. It is the national rate of urbanization that is being focused upon, either as the variable to be explained, or the as the variable doing the explaining. This is, in fact, the dominant mode of reasoning and analysis in the literature. Barring some exceptions,<sup>2</sup> the academic literature and policy mind‐sets have been squarely focused on the aggregate rate of urbanization. Moreover, the opportunities and challenges posed by urbanization are often taken to be synonymous with those offered and experienced by the main urban centers (i.e. the political or commercial capitals, or the “big cities”).

Take the case of Tanzania. According to the 2012 census, around 10% of the population lived in Dar es Salaam, the political capital. At around 4.5 million, this was the largest urban agglomeration in Tanzania by a huge margin. The population of Dar grew dramatically over the past 50 years and the bulk of this growth was accounted for by in‐migration (Wenban‐Smith, 2015). Facts such as these, seen in this way, have colored much of the urbanization discourse, in Tanzania, but also in the rest of the world. They lead to a focus on investment in large cities, in response to in‐migration. And because these are migrants from poor rural areas, the argument goes, public investment in countries’ metropoles is also of primordial importance to address poverty.

Consider, however, the following perspective, also taken from Wenban‐Smith (2015). Figure 1 shows that in 2012 Dar accounted for about one‐third of the urban population. But it also accounted for about one‐third of the urban population in 2002, 1988, 1978 and so on back. Thus, non‐Dar urban areas have grown as fast as Dar in Tanzania’s history. If we further divide non‐Dar urban into regional capitals (with an average population of around 200,000) and small towns (with an average population of around 20,000), an even more interesting trend appears— small towns are forming an ever‐increasing 2 For example, Henderson (2003), Kanbur and Venables (2007) and Christiaensen, De Weerdt and Todo (2013).