Domestically, the focus has been on rural-urban migration, without much distinction between urban areas. Yet, incipient evidence suggests that secondary towns may be more within the reach of the poorer segments of the population than large cities, and that secondary town development may hold more promise to improve job opportunities and for poverty reduction than metropolitanization. This is an area for further investigation with important policy implications for investment (Gibson, et al., 2017; Christiaensen and Kanbur, 2017). More broadly, a systematic documentation and incorporation of internal migration patterns in national development strategies (rural-urban, but also urban-rural, urban-urban and rural-rural, and return migration) remains lacking. More systematic use of the census data could help address this lacuna.

# **3 ECONOMICS OF MIGRATION AND JOBS**

The policy framework that we develop in this section is based on the spatial equilibrium model developed in Rosen (1979) and Roback (1982). The model assumes that workers move in geographic space to equalize “livelihoods” over time. Labor income is a key determinant of these livelihoods and therefore migration decisions are affected by the geographic distribution of job opportunities.<sup>16</sup> At any time, three key factors enter in the individual decision to migrate: 1) their expectations about job opportunities in the area(s) of destination; 2) job opportunities in the area(s) of origin; and 3) the costs associated with moving and realizing the prospects in the destination. If the expected gains in labor income net of migration costs are positive, people are expected to migrate.<sup>17</sup> This continues until a spatial equilibrium is established.<sup>18</sup> This model provides a benchmark to assess the efficiency of the distribution of workers across space and, by extension, the efficiency of the policies and regulations shaping this distribution.<sup>19</sup> In the absence of market or regulatory failures, there would not be a need for government intervention. In practice, however, there are several failures that affect the three factors driving migration decisions and that call for integrated/well-coordinated policy interventions (see Table 2). A first set are classic imperfections that affect labor, capital, and insurance markets and which are the usual focus of migration policy: 1) workers might not have sufficient information about the geographic distribution of job opportunities or the information they have is biased; 2) the distribution of skills across workers might not match the distribution of skills required by 16 Although our discussion puts jobs at the center of the migration decisions, in the New Migration Economics literature (Lall, Selod, and Shalizi, 2006), livelihood prospects are conceived broadly. They depend on economic prospects, such as the likelihood to be employed and earn a good living, build up assets and save for the future, but also on access to social goods and services (education, health), which are typically place-bound, as well as personal security, and psycho-social well-being.

17 Migration costs include the monetary cost of moving (transport), settling in (e.g. rent), and finding a job, but also the psycho-social costs of social adaptation and integration and regulatory barriers. 18 It is important to note though that while migration is often seen as a one-shot event, it is in effect a process of cumulative causation, with people’s action space (the actual set of destinations within a person’s reach) evolving (expanding/contracting) over time. This induces individuals to regularly reassess their “migration-equation”, making return-migration also an important reality (Ingelaere et al., 2017), and an integral, though somewhat neglected, part of migration management. 19 Forced migration, in response to sudden (or slow onset) shocks (natural disaster or conflict), can also be understood within this framework. Such events dramatically reduce the prospects for economic and personal security in the current location, creating a gap, often suddenly, where there might have been a spatial equilibrium before.