Spikes in Movement on Memorial Day

By Nishant Kishore, Navin Vembar

The first major US holiday of the summer season, Memorial Day, came with major spikes in gathering across the US. With many cities relaxing or lifting their social distancing ordinances, it’s not surprising that we saw these increases, but looking at the numbers tell a few stories.

We looked across 4 weeks of May weekend data and compared the number of unique devices that visited each county and census tract in the 3 prior weekends, on daily average, with the daily average of the number of unique devices that visited those same areas over the Saturday and Sunday of Memorial Day weekend. Note that we can’t compare change in visits to the same places last year, but the nature of COVID-19 is that an increase in the size of gatherings without containment increases the spread of the disease. Even internally, our analysis uses differential privacy and removes small tract and county data (anything with < 50 devices) to keep people’s information safe.

First, looking at the county-level data across the US, we see some obvious patterns. People went to the beach – either the lake or the ocean. Lake Tahoe, the Gulf Coast, the coast of Virginia are among areas that pop out with major upticks in visitors.

COVID Population

Looking at Chicago, we see a more than 5x increase in people who visited Lake Calumet and Kilbourn Park, one of the highest increases in the nation of visits to a tract.

Chicago COVID

The tracts along Virginia Beach also saw more visitors, but at first glance, they were seemingly more modest than changes elsewhere. A close look at the data, though, shows that people were flowing into the area up to two weeks earlier, making the change appear smaller than it actually was. In fact, in a number of places along the coasts, people had started flowing to the beaches throughout the month of March.

Virginia Beach COVID

Ocean City, MD is one of those places where more people were visiting on the prior weekend, but a sharp jump of more than 75% over the Memorial Day weekend compared to the prior weekend. Those of us in the District or Maryland area saw pictures of beachgoers in the news over the last few weeks. But what is also striking is the fact that all of Delmarva Peninsula saw an increase in visits, visible in pink. The other heavy visitation location in Maryland was Deer Creek Lake. 

Maryland mobility

Biloxi and Gulfport were also popular destinations. The shape of the census tracts here really emphasize where people were visiting – the beaches. The below is a picture of the Gulf Coast from the western panhandle of Florida and through Alabama and Mississippi. The narrow shape of the tracts really emphasizes that people visited beaches more than anything else.

Gulf Coast

Summer is coming and with it, people are going to want to move around. As state and local governments relax restrictions it becomes increasingly important that individuals continue to take precautions to protect themselves and their communities. This means continuing to wear masks, practicing adequate hand washing, following the guidelines suggested by the local health department and reducing the number of contacts that individuals or families have, even while on vacation.

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