Cuebiq’s data does not attempt to tie social distancing behavior to transmission rates of the coronavirus. And at 50 feet, the width of a basketball court, you would be more than eight times the recommended guideline for minimum distancing from the Centers for Disease Control and Prevention. But the data, which can be taken as a measure of how often people come near other people, show the extent to which Americans changed their behavior to slow the coronavirus and where that behavior is changing back.

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Most Americans began slowly decreasing the number of times they came near others in early March. In Los Angeles, Cuebiq’s data shows, contact between residents had its first big decrease on March 13, the day President Donald Trump declared COVID-19 a national emergency and six days before California issued the country’s first stay-at-home order. In Cook County, Illinois, which includes Chicago, contacts showed a drop on March 14.

On March 26, when Colorado and Kentucky issued stay-at-home orders, distancing was at its highest, as Cuebiq’s data shows that Americans came in close contact with one another about a quarter as often as they had in February.

Health officials say the dramatic change in behavior was necessary to slow the spread of the coronavirus and prevent hospitals from being overwhelmed.

Lauren Ancel Meyers, a professor at the University of Texas at Austin who leads a department that models coronavirus death patterns based on similar cellphone mobility data, said part of the reason New York City’s outbreak became an epidemic was that the region didn’t begin distancing until the virus was already actively spreading in the area. Other cities got ahead of their outbreaks, and that saved lives.

“If we had not intervened and done something to slow the transmission of the virus in March, the models suggest, we would have seen very large and devastating epidemics in many U.S. cities,” Meyers said.

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COVID-19, the disease caused by the coronavirus, spreads mainly through close contact, and a study published this month found that social distancing was the most effective way to prevent transmission.

Data from Apple Maps in May showed that Americans in certain cities began driving and walking around again. But Cuebiq’s data suggests that even as they’re moving about, Americans are coming nearby one another more often. The rate of nearness is less than half of February’s levels, and it has gradually increased since March. And in some of America’s most populous counties, including Los Angeles, Manhattan (New York County) and Miami-Dade, Florida, nearness is even lower than in the rest of the country.