By Arup Mitra, Ayush Singh* The million plus cities and other large cities comprise the bulk of the urban investment and undertake a wide range of economic activities. Migrants from all economic spheres are therefore, attracted to these cities for earning their livelihood and experiencing upward mobility. Even an informal sector worker gets better off by moving to a large city compared to a small town. Though the level of congestion and other diseconomies are enormously large in large cities, fresh rounds of investments keep pouring in, which in turn shift the curves representing the economies and diseconomies of scale. As a result, the optimal city size keeps increasing with every round of fresh investment flowing into the city. What happens to the thousands of small and medium sized towns? To begin with, very few of them have strong drivers of growth. Except the satellite towns, which are close to the large cities and receive parts of the economic activities spilling over from the la...