Why the developing world needs wider streets

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Cities enable cooper­ation. They allow people to specialize, to hire and be hired, to learn from one another, to build things together that none could build alone. Economists refer to the productivity gains that arise from human proximity as agglomeration effects.

The agglomeration effects of cities arise from two things: the physical proximity of buildings to one another, and the intra-city transport system that allows people to move swiftly between them. Buildings without transport are as useless as transport without buildings: the benefits of agglomeration depend on access, on the ability of people and goods to move efficiently across urban space.

This is where cities in poor countries often falter. As they expand, land is claimed and built upon in small increments, each one rational for the individual settler. These private claims – houses, workshops, stalls – are immediate, tangible, and necessary. But taken together, they crowd out something equally vital: the shared spaces that allow a city to function as a whole. Roads are too narrow, rail lines can’t be laid, and transit corridors are blocked. Commutes stretch and markets fragment, diminishing a city’s economic potential.

In nineteenth-century Europe and America, this tension between private use and public need prompted a historic rebalancing. Railway lines were driven almost to cities’ cores, huge termini were built, and vast fleets of trams rattled up and down wide new public roads built by destroying existing city fabric. A great age of civic architecture dawned, as town halls, museums, courts, parliaments, art galleries, churches and libraries rose up on prime central tracts. These investments were not just luxuries: they were what made industrial-era ag­glo­meration possible.

Today’s rapidly urbanizing cities face a similar moment of decision. With­out deliberate efforts to reserve and protect rights of way, they risk becoming collections of poorly connected settlements rather than integrated economic wholes. If they are to deliver on the promises of urbanization, they must make room for the roads, railways, and shared infrastructure that turns density into opportunity.

The public realm in nineteenth-century Europe

Medieval European cities often gave 90 percent or more of their land over to houses, businesses, and shops, leaving little for streets, let alone parks, civic buildings, and ...