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Aug 18, 2017 10:30:00 AM

Solar Eclipse Crowd Density Predictions

Posted by Melissa Burke

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The first solar eclipse since 1979 will be taking place on Monday, August 21st. This marks the first time in history that the solar eclipse will only be visible in the United States and the first time since 1918 that a solar eclipse will be visible from coast to coast.  

While the eclipse will be partially viewable across most of the US, as USA Today mentioned, the journey in which the moon's shadow sweeps across the Earth's surface will cross parts of 12 states that make up the path of totality from west to east: Oregon, Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina and South Carolina.

Around 12 million people currently live within that totality band and another 200 million people or so live within a day's drive of it. These states have been preparing for months for the larger than normal crowds that will be descending upon state parks, campgrounds, major cities, and rural areas alike. Many of these areas will be turning into tourist attractions when they had never been considered as ones before and the numbers could be staggering.

We thought it would be interesting to pull together a visual analysis of the population that lives within the band of totality on a typical day and compare that map to one that shows all of the people who end up within the path on Monday the 21st. Taking it a step further, we’ll also pull together an analysis of where out-of-state visitors came from and we’ll identify the different patterns of movement across the path of totality.

How We Put Together the Analysis

One of the data structures Skyhook uses for analyzing US data is the US Census block group. A block group is the smallest geographical unit for which the bureau publishes sample data and it contains between 600 and 3,000 people. There are around 220,000 block groups in the US and around 10,000 of them will go dark within the path of totality during the eclipse on Monday.

Our depersonalized and de-identified device data map below shows where all detected devices within these 10,000 block groups that make up the light orange band come from on a typical day. The darker orange clusters on either side of the band show the devices present within an approximate driving distance of 2 hours from the path of totality or less. For each census block group this map shows how far from home the detected users were between 11am and 2pm on Monday, August 14th.  

Pre-eclipse Map.png

What We are Expecting the Data to Show

Based on the amount of hype around the event over the last several weeks and the fact that the event is taking place at the end of the summer, we’re anticipating that large groups of people will be traveling towards the path of totality across the country. That being said, since an event like this has never happened before, it is impossible to accurately predict how many visitors each block group will get on the 21st.

We’re interested to see if certain areas within the path see higher volumes of out-of-state visitors than others depending on which parks or tourist attractions are present within different block groups. We also anticipate that the dark orange clusters around the path of totality on a normal day will move in and become part of the light orange band.

After the event we will pull the data and create the final map that shows what the actual counts were within the respective block groups. We’ll also create another map that shows which states people came from and will identify trends around their movements. Stay tuned later next week for that analysis. In the meantime get yourself some solar eclipse glasses and enjoy this rare event!