SENSEable City Laboratory

Assaf Biderman | associate director
Mauro Martino | interaction designer
Carlo Ratti | director
Andrea Vaccari | project leader

Special thanks to:

Jon Reades | data analysis
Francisca Rojas | text analysis
Caitlin Zacharias | text analysis


How does a city perform during a special event or a sudden emergency? Until today it has been difficult to monitor urban dynamics in real time. Traditional methods include head counts, surveys, aerial inspection, and satellite image analysis, but these are usually costly and slow to produce quantitative results. Our approach to understanding the city during special events such as the Presidential Inauguration aims to process existing information in real time from the telecommunications infrastructure. This includes mobile phone networks, which we consider to be a nervous system for the city, and which in turn has the potential to provide useful and rich information and services to citizens.

Mobile phones and wireless networks form a pervasive infrastructure that allows people to extract and insert information from almost any location and in real-time. This feedback loop has the potential to influence many urban functions and can help local authorities, service providers, businesses, and citizens themselves to improve the economic, social, and environmental sustainability of the places they inhabit. As a sketch of this future scenario, and to commemorate President Obama's 100th day in office, Obama | One People offers an unprecedented view of urban activity in Washington D.C. during his historic Inauguration on the week of January 20, 2009.

The data analyzed consists of hourly counts of mobile phone calls served in Washington, D.C. and includes the origin of the phones involved in the calls. To ensure the complete privacy of the mobile customers, analyses are performed in compliance with the 2002 Directive of the European Parliament and Council on Privacy. The use of aggregate call data implies that at no time can individual users be identified. As a comparison, consider information about highway traffic: we know how many cars from each state are traveling at any given time, but we do not know the license plate number or the individuals driving.


Obama | One People showcases the potential of our analyses by answering the questions: Who was in Washington, D.C. for President Barack Obama's inauguration? When did they arrive, where did they go, and how long did they stay? The event was truly international with people coming together from 138 countries, totaling over half of all the countries in the world. Among the foreign countries, the main international callers were from Canada, Great Britain, France, and Puerto Rico, which registered a five-fold increase in call activity. In the U.S., the top calling states were also the country's most populous: California, Florida, New York, and Texas. Notably, Georgia also figured in the list of top five callers on Inauguration day, even though it ranks ninth in U.S. population.

Examining the relative increase in call activity by state reveals some unexpected results. The states with the strongest increase were the southern states of Alabama, Georgia, Kentucky and Tennessee, with calls up to twelve times the normal levels. These are states that played a prominent role in the Civil Rights movement and notably are also so-called red states whose voting population went for the Republican candidate, John McCain. Other states with a ten-fold increase in call activity were Illinois, Barack Obama's home state, and Michigan, Ohio and Indiana, swing states which went blue, voting for President Obama. Most interestingly, comparing these results with U.S. demographic statistics shows that the percentage of African Americans in each U.S. state is a predominant factor determining increase in call activity and therefore participation in the event, which instead was not necessarily influenced by the state's proximity to Washington, D.C. or its political leaning.

Correlation between increase in call activity and percentage of African American

Analyses on call activity in the days before and after January 20 also reveal that the Inauguration was a multi-day event as mobile phone traffic increased markedly throughout the week. On Sunday, January 18th call activity began to increase and by Monday, calls were already two to three times what they would normally be on a Monday in January in Washington D.C. On Tuesday, January 20th, the day of the Inauguration, call activity reached unprecedented levels throughout the day and the network served six times more text messages than normal. On the morning of the 20th, call activity was two to three times larger than normal levels as the crowd was anticipating Barack Obama's oath, then call activity dropped as the crowd listened to President Obama's inaugural address, and after the speech concluded at 2pm calls peaked to five times the normal levels as people rejoiced.

Trends in call activity per locals, nationals, and foreigners

Geographically, our analyses show with striking clarity how the Inaugural visitors spread beyond the confines of the Federal areas of Washington, D.C. - such as the Mall and Pennsylvania Avenue - into the neighborhoods of the city. The hotspots of activity were clustered in the Northwest neighborhoods of the city, around Downtown, Adams Morgan and U Street. The historic inauguration of President Obama offered people from all over the United States and the world the occasion for a truly urban celebration. While these results are not surprising in themselves, the analyses presented in the Obama | One People project allow us to quantify and compare the presence of people in different areas of the city and to unveil their dynamic movements through time.

Press Materials
The material on this website can be used freely in any publication provided that:

It is duly credited as a project by the MIT Senseable City Lab. PDF copy of the publication is sent to

For more information,