Large sections of public life came to a standstill over the month of March as the novel coronavirus - which causes the potentially lethal respiratory illness COVID-19 - spread across the United States. State and local governments shut down schools, ordered restaurants and other businesses to close and issued stay-at-home orders for millions. But the public policy response hasn’t been uniform, and not everybody has stayed close to home.

Using data shared with Reuters by the Kochava Collective, an Idaho-based company that helps businesses evaluate the effectiveness of online ads, we’re able to see which counties in the United States saw people (and their phones) travel longer or shorter distances in the first few weeks of March than they did in February.

Location data from smartphones has been used by governments and public health officials to fight the outbreaks in South Korea and Singapore. By tracing the movement and contacts of people who have been infected, officials have been able to inform people who may have been exposed. The strategy faces regulatory hurdles in the United States and Europe, where privacy restrictions prevent sharing of personal data.

Anonymized smartphone data in the United States shows some interesting trends. People in larger cities and urban corridors were more likely to change their travel habits, especially in early March. By the end of the month, most U.S. residents were traveling dramatically less than they did in February, but social and demographic differences were strong predictors of how much that changed.