The car-traffic apocalypse of the total solar eclipse has begun

As many as 7.4 million Americans may be traveling to the path of totality, where the moon's darkest shadow will cut across the country. But this mass migration will most likely overwhelm small towns and cities with record tourism — and choke key roadways with gridlock traffic.

That's according to an analysis by Michael Zeiler, a cartographer at the mapping data and technology company Esri who is an eclipse chaser of 26 years.

"People should not casually expect to drive down on the morning of the eclipse," Zeiler told Business Insider.

Many who've journeyed to see the eclipse are doing just that, however, since clouds and stormy weather threaten to block a clear view of the sun — especially near the east coast, where one-third of the US population is located.

Lauren Lyons Cole, an editor at Business Insider, planned to drive to Charleston, South Carolina, to see the total solar eclipse. Because weather conditions there have deteriorated, however, Cole said she — and many people she overheard in a Savannah, Georgia, restaurant — plan to try their luck in cities farther west that have clear skies in the forecast.

Cole said she hadn't hit any terrible traffic on the way to Santee, South Carolina — but Zeiler expects the area to be riddled with cars. ("Don't go to Santee," he told Business Insider.)

Based on Zeiler's analysis, nearly 74.6 million Americans may determine it's the quickest to reach and see totality. Most probably won't make that trip, but the Zeiler's maps nonetheless illustrate the potential chokepoint.

In Oregon, however, which will be the first US state to see the moon blot out the sun, the mass influx of vehicles for the eclipse may have begun several days before the event.

A video taken Wednesday by a frustrated-sounding resident of central Oregon that KAPP-KVEW Local News posted to its Facebook page shows a line of cars stretching for all 4 minutes, 32 seconds of the video, for roughly 4 miles' worth of roadway.

"This is all heading into Prineville on a Wednesday, all the way up the mountain," she said in the video, which she recorded at about 11:32 a.m. PDT. "There is no accident. This is all for the lovely eclipse that is happening, and everyone trying to get into their camping spots."

She added: "Luckily, I'm heading the other direction. ... The cars next to us are going roughly 5 miles per hour, if not completely stopped."

Prineville, Oregon, is located about 120 miles southeast of Salem, Oregon. Zeiler expects it to be the sixth-most trafficked solar-eclipse-viewing location in the country.

Since it's so close, Prineville will most likely see some runoff.

Zeiler advises those who are making the journey to bring all the food, water, toilet paper, and other essentials they would need in case small-town stores have their shelves emptied by hordes of eclipse chasers.

"You need to plan to be completely self-sufficient," he said.

contributed reporting to this post.