Solar Eclipse Traffic: What Are the Roads Like?

The most anticipated celestial event of the year — the solar eclipse — is here, enchanting millions with midday darkness and leading to far fewer traffic jams in many areas of the United States than expected.

As of 6:40 a.m. MDT, traffic in Wyoming was backed up between Cheyenne and Casper as drivers made their way to a region where they will be able to see the total solar eclipse, according to local newspaper the Casper Star Tribune. Roads elsewhere in the state are more congested than usual, too.

A solar eclipse occurs when the sun and moon are aligned such that the moon blocks the light of the sun, casting its shadow on Earth. People in certain states in the U.S., from Oregon to Nebraska to South Carolina, will experience a total solar eclipse for up to 2 minutes and 40 seconds —these are the places in a 70-mile-wide (113 kilometers) band, called the path of totality, that are completely covered by the moon's shadow, according to NASA. Total Solar Eclipse 2017: Everything You Need to Know.

A partial eclipse is visible from places outside this band, but with increasing distance comes a smaller percentage of the sun that is covered by the moon (called the eclipse magnitude), motivating many to drive to places where they can experience maximum daytime darkness.

Many of the 12 million people who already live in the path of totality won't have to go far to get a good view of the total solar eclipse. Early estimates suggest the roughly 25 million people who live within a day's drive of the band may be on the road today, leading to a prediction that today could be one of the nation's worst traffic days, according to NASA representatives.

Madras, Oregon, one of the first places to experience totality in the U.S. today, at 10:19 a.m. local time, prepared for thousands of travelers by calling in the Oregon National Guard to direct traffic at highway intersections, according to local news channel KTVZ.

"A cosmic traffic jam" was predicted for today in Oregon, according to a bulletin issued by the department in June. Millions of travelers were predicted to drive to Oregon to view the completely obscured sun, according to the Oregon Department of Transportation.

While on Saturday Aug. 19, there were 11,000 vehicles traveling northbound through the southern Oregon town of Chemult, as compared to the usual 4,000, since then, traffic in Oregon has been lighter than was expected.

"What we think happened was that the arriving motorists were well dispersed over the calendar over the past couple of days and that has helped make things easier," Peter Murphy, spokesperson for the Oregon Department of Transportation (with a focus on central Oregon), told Live Science.

There are, however, certain pockets of congestion, such as at the Ogden Wayside in central Oregon, where, as of 9:30 a.m. PST today, eager eclipse viewers have parked their cars in a line on the side of the road.

"It's an extraordinary event and our goal here … is to keep people safe and make sure that traffic can keep moving," Murphy said.

Carbondale, Illinois — a particularly notable place along the path of totality because it will also be in the path of the next total solar eclipse, in 2024 — was already seeing an influx of visitors as of Friday (Aug. 18).

"Already overwhelmed by the amount of people and traffic in Carbondale. Goodbye Carbondale summer…" tweeted Twitter user Dallas.

To see a real-time map of eclipse traffic, including how current travel times compare to typical ones, check out this visualization tool from mobility data company INRIX.

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