Eclipse - Howe did it compare to 2017?

A month ago, a total solar eclipse traversed North America from Texas to Maine. It was only seven years ago that we experienced that last total eclipse in August 2017 that spanned the United States from Oregon to South Carolina. The paths crossed around St. Louis and Nashville, areas that were able to experience both eclipses. Because the 2024 eclipse path did not involve western states, the lack of highway network density was not as big of an issue as it was in 2017 where Denver (I-25), Salt Lake City (I-15) and Portland (I-5) only had one major north-south interstate leading to long recovery times. So, what were some of the things that were similar this time around and how were they different?

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What was the same?

The microsurge of post-eclipse vehicle traffic was similar between 2017 and 2024. In a matter of minutes freeway interchanges within the path of totality delivered large numbers of travelers to the interstate system. After totality had passed, congestion appeared. It took a few hours for congestion to reach its peak. In Oregon in 2017, peak congestion took about two hours to establish itself and that was consistent for what many of the metro areas observed in 2024. The extent of congestion was unlike any normal traffic event. We are talking 50 to 100 of interstate freeway operating well below free flow conditions. This repeated itself in 2024 in many locales. The peak duration of congestion in the western United States in 2017 was about 12 hours which was the same as what Vermont experienced in 2024. Travel from larger metropolitan areas within two to four hours of totality where congestion was greatest was similar between the two eclipse events. The lingering effects of eclipse traffic into subsequent days was also evident with both events. Similar in both cases were the public service announcements and warning of significant congestion

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What were some of the differences?

First and foremost, the weather played a significant role in dampening the travel impacts. Unsettled spring weather and cloudy conditions throughout Texas and into the Midwest lessened most of the impulse, discretionary travel. Because the 2017 eclipse was in the summer, much of the totality path was under clear skies which was not the case in 2024, especially in Texas. Many last-minute cancelations (including mine) occurred as trips planned for the greatest likelihood of clear skies were curtailed due to the cloud forecast. At the same time, Vermont which had the best forecast for clear skies approaching the eclipse, experienced extensive congestion and travel impacts. Vermont’s congestion exceeded the western states congestion experience of 2017, most likely due to very large metropolitan areas on the fringe of the two to four-hour drive time to totality (Boston and New York). Vermont had congestion span over 100 miles, and while that is only slightly greater than in the west for 2017, there were four interstate freeways in close proximity, unlike the large western states where there was one per state.

The path of totality and the cloudy weather played a significant role in affecting Texas traffic reducing discretionary travel. The “extra” travel of eclipse chasers never materialized. Congestion cleared up in Texas quickly compared to the rest of the country. Between large freeways in the metro areas of Texas, the cloudy weather, the fact that totality directly passed over three of the largest metropolitan areas, and the presence of “virtual work from home” opportunities had an impact on lessening congestion.

The 2017 eclipse occurred in the summer, when people take time off for vacations. The 2024 eclipse was in the spring when more people are working which also affected last minute discretionary travel planning (less in the spring than the summer). Not to mention the weather – 2017 it was warm and mostly clear across the United States. Spring weather in the US was spring-like in its questionable nature and for Texas unseasonably cloudy. This lack of certainty played a role in the decisions of people choosing whether to travel in 2024.

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As second big difference in 2024 was the direct hit (or near miss) of totality with large metropolitan areas. In 2017 the only direct “hits” were Kansas City, St. Louis, and Nashville. In 2024 the list included San Antonio, Austin, Dallas-Fort Worth, Indianapolis, Cleveland, Niagara Falls/Buffalo, Syracuse, and Montreal. This allowed substantially more viewing to be without travel than in 2017. The number of near-miss metropolitan areas (either just outside totality or a two to four-hour drive was comparable. In 2017 ten cities were adjacent to totality: Portland, Salt Lake City, Denver, Memphis, Indianapolis, Cincinnati, Louisville, Chattanooga, Atlanta, and Charlotte. In 2024 the list grew to 13: Houston, Oklahoma City, St. Louis, Nashville, Memphis, Chicago, Louisville, Cincinnati, Columbus, Detroit, Pittsburg, Toronto, and Boston. In the case of St. Louis and Nashville, which experienced both eclipse events, the event likely self-promoted itself from the prior eclipse. This, combined with a clear sky forecast between the two metro areas, led to some of the more extensive congestion in the United States comparatively speaking.

A third factor was the time between eclipse events. Prior to 2017 there had not been a transcontinental total solar eclipse for nearly 100 years (or any total solar eclipse since February 1979). In 2024, it was just seven years later. This helped with recognition of the events magnitude both for the attraction to travelers and to the planners for preparation.

One thing that was different between metropolitan areas was the duration of congestion. For example, Dallas-Fort Worth was back to normal within about four hours and San Antonio about six hours. Whereas the four interstates exiting Vermont (I-87, I-89, I-91, and I-93) did not settle for 10 to 12 hours. St. Louis, Nashville and Indianapolis experienced 9 to 11 hours. Vermont can be explained due to the lack of east-west interconnections, two-lane interstates (in Texas they are double that and more), clear sky forecasts and large metropolitan areas to the south. It seems clear sky play a key role in the intensity of congestion and travel as St. Louis and Nashville (which both experienced the eclipse in 2017) were some of the more congested metro areas. Indianapolis had adjacency with a large metro area (Chicago) and presented a closer (with more services) destination resulting in the I-65 corridor experiencing congestion for 10 hours.

The time to peak congestion also varied by metro region. While 75 percent of the observed metro areas/corridors reach peak congestion between 1.5 and 2.5 hours (averaging two hours). The other six corridors averaged nearly 6 hours. Three of these were Vermont related (I-89, I-91, I-91) and its adjacency to Boston and New York. The other three (I-40 Memphis 130 miles, 1-79 Pittsburgh 80 miles, and I-65 Chicago 160 miles) relate to large metro areas near but outside totality). These three cases appear to combine a large metro area outside totality with an interstate route linking to another metro area within totality (Little Rock with Memphis, Indianapolis with Chicago and Erie with Pittsburgh). This combination likely allows for delayed departures (due to service availability) that would not be the case in situations like St. Louis, Nashville (with nearby metro areas in totality) or other edge-adjacent metro areas that were partially in totality.

This time around there was extensively more collaboration on traffic management and preparation based upon the events of 2017. Many locations declared a state of emergency opening access to additional resources. This was helpful, but in the end what we learned in 2024 was that the most significant factors that played a role in congestion included:

·??????? Weather – extended forecasts and actual clear skies result in more travel.

·??????? Proximity of large metro areas near, but outside totality. This creates significant discretionary local travel and potential for extended tourist travel (fly in and drive).

·??????? Awareness of the spectacle – St. Louis and Nashville being areas that experienced both, had greater congestion in 2024 than most other metro areas.

·??????? Lack of interstate density and interconnectedness – in the Midwest and East there are numerous east-west and north-south interstate freeways as well as many national highway system routes. This density was very apparent in the urbanized areas of Texas which experienced totality pass overs. Wherever density and connectedness were not present, congestion was more extensive.

·??????? Most direct hits of totality to metro areas reduced travel. Whether the weather or the fact that many large metro areas were within totality reducing “adjacency travel” by population centers, a good stretch of the totality path from Ohio to Pennsylvania to New York seemed to experience less congestion. Specifically, Cleveland and Buffalo were examples (maybe the barrier of the Great Lakes played a role in these cities).

The final episode of the series (#5) will explore the next transcontinental eclipse in 2045. It will offer ideas to consider in transportation investment planning in the next 20 years that can capitalize on both independent utility and the potential to reduce eclipse congestion impacts.