Brett Kelman | Nashville Tennessean

But in dozens of rural counties, movement has dropped my less than 25%

In Nashville, Memphis and Williamson County, daily travel is down by nearly half.

Nashville residents have cut daily movements in half since coronavirus first came to the city, but rural counties across Tennessee have made much less progress towards slowing the outbreak, according to data collected from millions of smartphones.

This phone data contributed to Gov. Bill Lee's Thursday decision to lock down the state by ordering residents to stay in their homes. The governor previously resisted this action, choosing instead to urge — not order — residents to stay home. But Lee said a combination of phone tracking and traffic flow data ultimately changed his mind.

“We clearly saw data in the last two or three days that changed the movement of Tennesseans, and that was very worrisome and it was also very dangerous,” Lee said. “It’s hard to know why that has happened. We just know that it has.”

This cellphone tracking data, released online by technology startup Unacast, offers a rough measurement of how many residents are staying inside and avoiding travel and gatherings. In four counties where the virus has hit hardest — Davidson, Shelby, Williamson and Sumner — data shows the movement of cellphones decreased by 50%, 44%, 49% and 46%, respectively. Most of the largest drops occurred on the same dates that city officials shut down schools and closed non-essential businesses.

But this pattern does not hold up across the state. Beyond the reach of city mayors who acted early to fight the virus, reductions in daily travel have been much smaller.

In 16 Tennessee counties, some rural and sparsely populated, daily movement had declined by 25% or less, the data showed on Friday morning, based on cell tracking performed four days prior. Many of these counties have reported only a few coronavirus patients so far, but the risks of exposure, illness and death remain.

{{props.notification}} {{props.tag}} {{props.expression}} {{props.linkSubscribe.text}} {{#modules.acquisition.inline}}{{/modules.acquisition.inline}} ... Our reporting. Your stories. Get unlimited digital access to exclusive content. Subscribe Now

The smallest change in all of Tennessee was reported from Marion County, west of Chattanooga, where daily travel had dropped by only 1%. The county has seen at least 14 cases of coronavirus and one virus-related death.

Alan Poizner / For The Tennessean

On Thursday, Lee spoke directly to Tennesseans in an effort to convey the risk to all.

“We need you to understand that home isn’t an option,” he said. "It’s a requirement for the swift defeat of COVID-19.”

'It does not appear people recognize the severity of the problem'

The Unacast cellphone data, collected for advertisers and retailers but now repurposed to study social distancing, offers more fodder to public health advocates who've argued the Lee administration acted too timidly in response to the coronavirus.

The governor initially resisted pleas from medical professionals to shut down the state. On Monday, he issued a statewide order "strongly urging" Tennesseans to stay inside but stopped short of mandating them to do so to "protect personal liberties."

View | 274 Photos

Coronavirus in Tennessee: Impact felt throughout state

In response, doctors repeatedly argued the wording of Lee's order did not match the seriousness of a deadly pandemic.

“I don’t know about you, but if you’ve driven past grocery stores or Home Depot, I see these parking lots are full," said Dr. Tufik Assad, a critical care physician at Williamson Medical Center. "It does not appear people recognize the severity of the problem. And I think part of that issue is that an urge and a mandate carry different weight."

Other doctors have criticized how Lee has allowed many businesses to keep operating. Dr. Aaron Milstone, who has led the campaign to pressure governor, said the broad language of the governor's executive orders allows businesses from electronic stores to driving schools to stay open.

Kelman, Brett M

For example, Hobby Lobby, a craft store that police forced closed in four states, continued to operate in Nashville under an exemption that applies to business selling work-from-home products.

“You can go to any smaller, rural community across the state ... and find businesses open that shouldn’t be open because they fall under this broad umbrella of essential business,” Milstone said. “There are so many holes in this urging that without a mandate you’ve given everyone a loophole to stay open.”

Lee said Thursday he was not considering adjusting his executive order to close more businesses but stressed that his decisions are fluid.

Travel slowed after Tom Hanks got sick

Unacast, a Norwegian company with offices in New York, is a small part of a little-known industry that gathers location data from cellphone apps, often without the user’s knowledge, and analyzes it for retailers and advertisers. The company says it gathers anonymous information from “tens of millions” of phones, then extrapolates that data to apply to the entire population.

In this case, the data has been applied to Unacast’s free Social Distancing Scoreboard, which the company plans to update and expand as coronavirus spreads.

According to the Unacast scoreboard, daily travel in Tennessee has fallen 38% as of March 29. The data is updated daily but lags by a few days to ensure accuracy, the company said. Because the data lags, it does not yet show the impact of the executive issued by Lee on Monday or Thursday.

But the data does show how the virus has impacted movement over the past few weeks. Daily travel began to drop on March 11 — a stunning day in the development of the pandemic. In a span of a few hours, several major stories broke: The stock market plummeted, President Donald Trump banned some travel from Europe, the NBA canceled its season and actor Tom Hanks and his wife announced they had the virus.

Dr. David Aronoff, an expert on infectious diseases at Vanderbilt University Medical Center, said this week the Unacast data is incomplete, but it appears to quantify shortcomings in a statewide response to the virus.

“This data isn’t granular — it doesn’t tell us what the purpose of movement was — but it does suggest there is more we can do in this space,” Aronoff said.

The Unacast data also appears to show what is working. In some communities, where social distancing restrictions have been mandated for weeks, patterns have emerged.

The cities of Nashville, Memphis and Knoxville were among the first communities in Tennessee to detect the coronavirus, but travel in these cities didn’t drop dramatically until about a week later, when schools were closed to prevent exposure to the virus.

Several days after that, mayors in all three cities issued stay-at-home orders that closed non-essential business. The result in each city was the same: A one-day increase in travel, likely as residents stocked up on supplies, then travel falling to its lowest point on the final day of data collected by Unacast.

Unacast did not answer questions about exactly how it collects location data from cellphones or what apps send them this information. A company spokesperson said the data is "anonymous" and the technology that extrapolates results is proprietary.