The economic fates of diverse cities such as San Francisco, New York and Detroit would seem to be vastly different – but they share a common thread

Over the last half-century, the story of America’s cities is a tale of booms and busts. New York and tech hubs like San Francisco – once cities in financial distress – have transformed into economic powerhouses. At the other extreme, one-time prosperous manufacturing cities like Detroit now find themselves in economic turmoil.

Viewed in isolation, the economic fates of these cities would seem to bear little resemblance to each other. However, they all share a common thread: since 1970 these cities, like nearly every other major American city, have experienced a “hollowing out” of the middle class.

The graphic above shows the change in income distribution in 20 major US cities between 1970 and 2015. In 1970, each of these cities exhibits a near-symmetrical, bell-shaped income distribution – a high concentration of households in the middle, with narrow tails of low and high-income households on either end. By 2015, the distributions have grown more polarised – fewer middle-income households, and more households in the low-income and/or high-income extremes.

The growing polarisation of wealth in US cities is quite stark when viewed geographically. The maps below show the changing distribution of wealth in four US cities between 1970 and 2015. All dollar amounts are adjusted for inflation.



New York

Click on 1970 or 2015 to see that year’s income distribution

New York in the 1970s was a city in full-on economic distress. Unemployment topped 10%, a ballooning public debt brought the city to the brink of bankruptcy, and residents were fleeing from the city centre to its suburban outskirts.

Fast forward to 2015 and the pattern has reversed. New York is among the wealthiest cities in the country, with the heaviest concentration of wealth in central Manhattan. Residents living in the purple areas in the map have median household incomes of greater than $120,000. In Manhattan’s wealthiest areas, the tallest purple spikes, median household incomes exceed $250,000.

Despite New York’s good economic fortunes, low income areas (those coloured white-yellow) remain as numerous today as they were in 1970. Today they comprise 42% of New York’s Census tracts v 43% in 1970.

San Francisco

Click on 1970 or 2015 to see that year’s income distribution

In 1970, San Francisco’s income distribution is notable for the absence of high-income neighbourhoods. Of the 196 areas shown in the map, none had a median income high enough to reach the top two income tiers (those coloured dark red or purple). The city itself resembles a sloped plane, with incomes gradually declining from their highest point in the south-west to their lowest point in the north-east.

Since then, San Francisco’s economic geography has undergone a complete reversal. Today, it is predominantly a city of upper-middle to high-income households. The once low-income neighbourhoods in the city’s north-east, near its urban core, are today its wealthiest.

Detroit

Click on 1970 or 2015 to see that year’s income distribution

In 1970, Detroit was one of the wealthiest cities in the US. By 2015, the wealth appears to have radiated outward from its sunken, white centre to its fringes. Even in Detroit, a city that is now synonymous with economic distress, the number of high income areas (dark red-purple) has remained largely unchanged since 1970.

Chicago

Click on 1970 or 2015 to see that year’s income distribution

Like its Rust Belt neighbour Detroit, Chicago boasted a thriving manufacturing sector in 1970. Incomes were lowest in the city centre, growing higher radially outward toward the city’s borders.

Chicago was largely successful transitioning away from manufacturing to a service-based economy. This shift is evident in the bifurcated pattern present in 2015 – a heavy concentration of wealth in the business/financial district and marked decline in the surrounding area.

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