It’s a big day for America, for a few minutes this afternoon it’s going to get dark before the sun sets. That’s not because of witchcraft, it’s instead because the moon will pass in front of the sun in the first total solar eclipse to be visible in the U.S. since 2017. After that happens, there’s going to be a lot of traffic as everyone heads back home.

Millions of people are predicted to be traveling to view today’s solar eclipse, which kicks off at around 12:06 p.m. CDT with a partial eclipse in Texas before going total at around 1:27 p.m. CDT. The path of the eclipse is a three-hour drive away from eight cities with a population of more than 2 million people, and Time reports that this means there’s going to be some really bad traffic when they all decide to head home.

In a new reports from the outlet, experts have predicted that if everyone leaves their viewing areas at the same time once the eclipse passes, the traffic on U.S. highways could be worse than if the crowds attending 71 sold-out football games all drove off at the same time. As Time explains:

At least 5 million people traveled for the 2017 eclipse, according to a journal by the Institute of Transportation Engineers, but even more are expected to gather to witness this year’s total solar eclipse on April 8. Already, an estimated 31.6 million people currently live in the roughly 115-mile wide path of totality—compared to the 12 million that did in 2017. “Having a total solar eclipse pass through the U.S. is kind of like having 20 or 30 Super Bowls happening all at once,” says Richard Fienberg, project manager of the American Astronomical Society’s Solar Eclipse Task Force. “So many people are gathering for the spectacle over a long distance.”

To try and mitigate the jams that could clog America’s roads, the Federal Highway Administration has advised viewers to “drive early, and stay longer” wherever they plan to view the celestial anomaly. This way, they could miss the worst of the traffic, but with more than five million people predicted to be traveling for the eclipse, there’s bound to be jams wherever you turn.

In Arkansas, state officials told Time that its “Interstates and highways could be tested” as up to 1.5 million people descend on the eclipse’s path through the region. Officials warned that AR Highway 70 to Benton and AR Highway 65 from Conway to Greenbrier could be the worst affected. In Texas, I-35 could be jammed as it’s a “significant corridor” to many areas where the eclipse will be visible.

What’s more, with a spike in traffic collisions projected for today’s eclipse, experts are issuing further warnings to drivers to stay safe on their way to and from their solar eclipse viewing party. So remember, plan your drive there and back carefully, be prepared to wait in line and don’t lose your cool. Let’s all have a nice, safe eclipse today, OK?