Figure 1: Urban growth in Lagos, Nigeria Lagos: population and built-up landIndex (1990 = 100)01002003004001990200020102020PopulationBuilt-up land© EAGLE BE...

(a) Urban describes an area with a high concentration of people and buildings, where most employment is in non-primary activities such as manufacturing and services. (b) 2010. (c) 2020. (d) 40 index points: population was 250 and built-up land was 290. (e) Lagos attracts migrants because it has a wider range of jobs, including port, trade, construction and informal-sector work. (f) Expansion of housing can use land previously occupied by farmland, wetlands or open space. (g) Built-up land can grow faster because new migrants and existing residents need homes, roads, shops, schools and workplaces, not just houses. Low-density development on the city edge uses a large amount of land per person. Higher-income households may move to suburban estates with larger plots, while industries and warehouses need extensive sites near transport routes. Informal settlements can also spread onto unused or marginal land. Therefore, even where population increases, the area covered by urban land can increase at a still faster rate.