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The data, released to ABC News by Descartes Lab, measures how many miles the typical individual cellphone ventured from its starting point three weeks ago on March 9 and shows how it's changed in the weeks since.
Let's take San Francisco. On March 9, the day the Grand Princess cruise ship docked in Oakland, the typical resident moved 1.7 miles from their home. The next week on March 16th, the day the city announced its shelter in place order, the typical resident moved one mile from their home. And the next week, on March 23rd, residents moved just a few feet from their home. Overall, that is a 99% reduction in movement over two weeks.
Alameda, Contra Costa, Marin, San Mateo, and Santa Clara counties all have similar numbers in reduction ranging from a 92% to 98% shift in movement. Napa and Sonoma Counties, however, have lower numbers with 72% and 78% reductions in movement, respectively. Those two counties were later to enact a shelter in place order.
While the Bay Area has overall shifted its movements drastically, not all parts of California have made the same adjustments. In the Central Valley, Fresno County has a 71% change in movements over the past three weeks. Merced County has a 52% change in movement. Overall, Californians went from moving on average 3.9 miles from their home on March 9 to moving 0.6 miles from their home on March 23. That's an 85% decline in movement over three weeks.
The state of New York, on the other hand, has had a 99% shift in movement across the state.
We asked ABC7 News special correspondent Dr. Alok Patel if the increase in people staying at home in the Bay Area is reflected yet in flattening the curve.
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"It's really hard to say right now if we're flattening the curve," Dr. Patel said. "I think the good new is, something to be optimistic about, is we haven't seen quite the surge in the Bay area that we're seeing in other parts of the country."
It's likely the Bay Area could still see a surge in cases, but the Bay Area was the first region to order a shelter in place and that could make a difference.
"I don't see how anyone can't say it makes a difference," Dr. Patel said. "It took us about two to three weeks to really nail sheltering in place on the head and that has to have some kind of correlation in the amount of cases we either have seen or are going to see."
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