The New Yorker has published a beautiful infographic tracing inequality along New York city’s subway lines. It reveals, for example, that the gap between the median household income in the areas immediately surrounding the Chambers Street stop in Lower Manhattan and the East 180th Street stop in The Bronx is $191,442.

But is this yawning divide a problem, as The New Yorker insists? Or should it be understood in some other way? In The Triumph of the City, Harvard economist Edward Glaeser offers a different view:

Cities aren’t full of poor people because cities make people poor, but because cities attract poor people with the prospect of improving their lot in life. The poverty rate among recent arrivals to big cities is higher than the poverty rate of long-term residents, which suggests that, over time, city dwellers’ fortunes can improve considerably. The poorer people who come to cities from other places aren’t mad or mistaken. They flock to urban areas because cities offer advantages they couldn’t find in their previous homes. The great problem of urban slums is not that there are too many people living in a city, but that those residents are often too disconnected from the economic heart of the metropolis. The great masses of the urban poor do create challenges that must be faced, and those are the topic of the next chapter, but it’s far better to hope for a world where cities can accommodate millions more of the rural poor than to wish that those potential migrants would end their days in agricultural isolation.

As Glaeser goes on to explain, the absence of poor people in a city can be understood as a sign that a city lacks things like affordable transportation options and housing. Efforts to improve the lives of the urban poor — by lowering the cost of housing and transportation, among other things — will actually attract more poor people to the cities that undertake them.

So The New Yorker is missing the real story: the fact that a poor person can get on the subway at East 180th Street and travel to Chambers Street at relatively low cost is an enormous boon, as it means that she has easy access to service jobs catering to high-earners without having to purchase and maintain an automobile. When rich and poor and geographically isolated from each other, in contrast, economic transactions that would greatly benefit the poor are less likely to take place.

The central problem facing poor people in New York city isn’t inequality as such. Rather, it is the fact that local land use regulations have restricted the supply of housing, thus raising its cost enormously. This has led many poor people to migrate to low-cost regions in the Sunbelt, which are less unequal than New York city but also less productive. In cities like Houston and Dallas, poor people can find more affordable housing, yet they face much higher transportation costs, which limits their ability to access the kind of affluent customers they can access more readily in New York city.