Cities exist, grow, and prosper because they take advantage of scale economies and specialization wrought by agglomeration. But output growth inevitably stresses transport infrastructure because production requires space and mobility. To prevent congestion from crowding out agglomeration benefits and to expand the supply of urban land, cities must invest in transport infrastructure. Yet balancing the growing demand for infrastructure with its supply is often difficult. In particular, many cities lack the funding to maintain and expand streets and urban highways.

This paper explores the challenges and opportunities that government officials face in designing coherent 'rules of the game' for achieving urban sustainability during times of growth. Sustainability is judged by three criteria. The first involves elements of day-to-day quality of life, such as having clean air and water and green space. The provision of these public goods has direct effects on the urban public's health and productivity. The second focuses on the city's greenhouse gas emissions.

Housing matters to the livability of cities and to the productivity of their economies. The failure of cities to accommodate the housing needs of growing urban populations can be seen in the proliferation of poorly serviced, high-density informal settlements. Such settlements are not new in the history of rapidly growing cities, their persistence results as much from policies as from economics and demographic transition. Slums have attracted most of the attention on urban housing in developing countries, and the Millennium Development Goals have given prominence to their reduction.

Extension services are a keystone of information diffusion in agriculture. This paper exploits a large randomized controlled trial to track diffusion of a new technique in the classic Training and Visit (T&V) extension model, relative to a more direct training model. In both control and treatment communities, contact farmers (CFs) serve as points-of-contacts between agents and other farmers. The intervention (Treatment) aims to address two pitfalls of the T&V model: i) infrequent extension agent visits, and ii) poor quality information.

This Fifth Edition of the Uganda Economic Update presents evidence that if the urbanization process is well managed, it has the potential to stimulate economic growth and to provide productive jobs for a greater proportion of Uganda’s young and rapidly expanding population. In many countries across the world, the growth of cities has stimulated the establishment and expansion of productive businesses by reducing the distance between suppliers and customers. The growth of cities has also facilitated provision of social services and infrastructure through economies of scale.