Visualizing the Footprint of Highways in American Cities

Driving on the open road is a defining feature of the American experience, made possible by coast-to-coast highways. It defined a generation of life and ingrained the automobile into the urban fabric of American cities, for better and worse.

Today’s animations show how highways reshaped the downtown cores of six American cities and created new patterns of urban life. But first, some background information on the creation of the interstate system.

The Interstate Highway System

The U.S. Interstate System was created on June 29, 1956, when Dwight Eisenhower signed the Federal-Aid Highway Act. It would eventually run 46,876 miles, cost $521 billion and take 36 years to complete.

From San Diego to Bangor, the interstate highway system connected Americans and opened up the country to commerce and geographic mobility like never before, but for all its benefits, this new transportation network ripped through established patterns of urban and town life, creating a new era of urban development.

The Legacy of Highways: The Suburbs and Inner Cities

The vast geography of continental America helped to entrench personal mobility and freedom into American society. Highways and automobiles accelerated this lifestyle and even changed the shape of entire cities.

According to Prof. Nathaniel Baum-Snow of the University of Toronto, between 1950 and 1990, the population of central cities in the U.S. declined by 17% despite a population growth of 72% in larger metropolitan areas during the same period. Baum-Snow posits that, had the interstate highway system not been built, central cities’ populations would have increased 8%.

Firms followed the workers to the suburbs, but the highways system also created additional benefits for these firms. Cross-country road access freed manufacturing from ports and downtown rail hubs, while allowing economies to operate across larger distances, altering the dynamics of typical urban economies.

Faced with this new reality, inner cities struggled in years to come.

Inner Cities

The introduction of highways created an increase in the supply of land for development through faster commutes to outlying areas. In 1950, half of all jobs were located in central cities. By 1990, less than one-third of urban jobs were located in the core of American cities.

“Not TV or illegal drugs but the automobile has been the chief destroyer of American communities.” Jane Jacobs, Author The Death and Life of Great American Cities

Benefits of new development accrued to the outer areas while the construction of the highways in inner cities displaced largely low-income communities, segregated neighborhoods, increased the amount of air and noise pollution, devalued surrounding properties, and removed access to jobs for those without a car, further concentrating poverty.

Before and After: Six American Cities

A bird’s eye view of six American cities reveals what was and what is now. By overlaying existing highways over the neighborhoods they replaced, it becomes clear how much interstate construction drastically altered America’s urban landscape.

Public opposition to the construction of I-980 was so strong that developers abandoned the project in 1971, only to complete it over a decade later.

The I-95 carved through Miami’s largely black Overtown neighborhood. The construction of a single highway cloverleaf resulted in 20 square blocks being demolished, displacing over 10,000 people in that community.

The I-95 comprised unconnected segments between 1957 and 1965 through the densest urban areas in a deliberate effort to prevent premature suburbanization and to revitalize the downtown core.

The I-71 cuts downtown Cincinnati off from its waterfront and a massive freeway interchange forced the destruction of dozens of blocks west of downtown.

Freeway construction transformed Detroit between 1951 and 2010. Previously, its downtown had been surrounded by a high-density street grid. Today, it’s totally encircled by freeways.

Rochester is one of many cities opting to undertake freeway removal projects.

As the dotted line above shows, the “moat” surrounding downtown is slowly being removed. The city used reclaimed land from the Inner Loop freeway to construct three mixed-use developments that include below-market-rate units.

The Future of Urban Living: Do Highways Matter?

A new era of living is reconsidering the impacts of these highways on urban centers. As property values rise and existing housing stock is pressured, there are growing concerns over the environmental impacts of suburban life. As a result, urban planners and residents are looking to revitalize city cores and re-purpose land occupied by burdensome slabs of highway concrete.

Since 1987, there have been more than 20 urban highway segments removed from downtown cores, neighborhoods and waterfronts, mostly in North America. The pace of removals has picked up significantly and an additional 10 highways are now planned for removal in the United States.

During the COVID-19 pandemic, American cities have seen their traffic plummet. Rush-hour trips into cities are taking nearly half the time while some are not even commuting at all.

While this situation is likely temporary, it is offering a moment for reflection of how cities operate and whether the car should be at the center of urban planning.

*Hat tip to Shane Hampton, whose 60 Years of Urban Change compilation served as inspiration for this article. Visit that page for many more examples of highway impact on cities.

Staying Put: The COVID-19 Commuter Decline

Every day, millions of people worldwide rely on public transport networks to get around. But in times of crisis, bustling cities with high volumes of commuter traffic can come to a dramatic halt.

Today’s chart breaks down daily data from Citymapper’s Mobility Index, according to trips planned on the transport app across 41 select cities.

The results paint a unique picture of how social distancing and lockdown measures are impacting commuter and economic activity in major urban hubs.

Cities With the Biggest Drops in Activity

As the government response to the COVID-19 pandemic intensifies and people are urged to stay home, transit activity is dropping everywhere.

However, some areas are seeing more of a reduction in activity than others. Where has activity declined the most over the month?

*Note: Data measures the % of city moving compared to 100% baseline.

Overall, Vienna and Lisbon are the cities with the biggest average drop in commuter activity over the past few weeks. This decline in mobility is correlated with a spike in the proportion of COVID-19 cases in the population:

• Austria
  March 4: 2.6 per million
  March 25: 586 per million
• Portugal
  March 4: 0.4 per million
  March 25: 232 per million

That said, not every city is seeing a precipitous decline in activity — let’s look at those next.

Standing Still, or On Guard

Cities that saw lower decreases in commuter activity over recent weeks can generally be slotted into three categories:

1. Cities that were already on or near shutdown (Seoul, Milan)
2. Cities that have so far avoided major impacts from the virus (St. Petersburg)
3. Cities that successfully mitigated spread (Singapore)

Here are the 10 cities on the list that saw the lowest changes in activity:

*Note: Data measures the % of city moving compared to 100% baseline.

St. Petersburg is still seeing commuter activity at 69% of normal levels as of March 25th, as the proportion of confirmed COVID-19 cases in Russia remains low, at roughly 3.4 per million.

Milan has the lowest activity of any city at 3%, and has been in shutdown for most of the month.

Although Singapore’s total COVID-19 cases grew from 18.8 to 95.4 per million, it still has 62% commuter activity. Interestingly, Singapore is one of the few countries that has been able to properly control and manage its COVID-19 outbreak.

Biggest Weekly Declines

As the month progressed, various cities showed stark one-week declines in commuter activity based on official healthcare recommendations and growing case numbers.

After a government lockdown announced on March 9, Rome experienced the sharpest decline of -75% commuter activity in the week from March 4 to March 11. Currently, there is only 5% activity compared to usual, similar to Milan.

In the second week of March, COVID-19 cases in France jumped fourfold, from 27.3 per million to 118.4 per million people. As a result, Lyon saw a whopping -91% drop in commuter activity—going from 97% on March 11 to 6% on March 18.

Over the past week, as cases in Australia reached 95 per million, Sydney and Melbourne exhibited the highest average declines at -36% and -33% in commuter activity respectively.

Full List of 41 Cities

Here’s the full list of cities, courtesy of Citymapper.

*Note: Data measures the % of city moving compared to 100% baseline.

The COVID-19 pandemic is affecting everything from the stock market to the environment. With cities actively working to keep populations in isolation and healthy during this time, it may take a while before commuter activity returns to normal.