PORTLAND, Ore. — Traffic was still moving relatively well in Oregon on Sunday, a day before the first coast-to-coast total solar eclipse in the United States since 1918.
The eclipse is expected to draw up to a million people and clog roadways in Oregon — where the moon's shadow will first make landfall. Crowds have begun filling campgrounds and hotels for hundreds of miles.
But the Oregon Department of Transportation said traffic was rolling pretty smoothly early Sunday afternoon. Tom Fuller of the Transportation Department says traffic is expected to get heavier as the day progresses.
"We are starting to see an uptick on highways," Fuller said.
RELATED: Oregon wildfire causes evacuations in prime eclipse zone
So many people are camping on farm fields and wild lands in rural areas that animals are being pushed onto roadways, Fuller said. That is causing an increase in collisions between animals and vehicles.
"Deer and other wildlife are being pushed into traffic at higher rates," said Paul Woodworth, a manager with Oregon DOT. He said there were 11 collisions between vehicles and wildlife Saturday.
On Sunday in Salem, Oregon, eclipse enthusiasts camped in a small field across from the state fairgrounds where the Oregon Museum of Science and Industry will host an eclipse-watching event for 8,500 people.
Hilary O'Hollaren arrived Saturday with her two children, plus a friend and her son, to snag a space for the event.
"My friend and I are always up for an adventure," O'Hollaren, of Portland, Oregon, said. "It's one of those 'check the box' kind of things in life."
Traffic in central Oregon started picking up Wednesday as 30,000 people poured in for a large festival near the town of Prineville, creating miles-long backups on U.S. 26. Across the Northwest, planners are bracing for more of the same.
In neighboring Idaho, up to 400,000 people could show up. Major traffic jams also are expected in Washington state as people try to drive south or east to prime viewing locations.
Officials have also been grappling with the possibility that cloudy weather, closed roads or coastal fog could prompt eclipse-watchers to change plans at the last minute, throwing traffic into chaos.
More than two dozen wildfires are burning around Oregon, and nearly a dozen of them are in the path of totality, where the moon will completely black out the sun.
One of the most troublesome blazes is and around the Mount Jefferson Wilderness Area, a prime eclipse-viewing spot. Hundreds of people who intended to camp there or hike up Mount Jefferson to catch a stunning view of totality have had to change their plans.
Campfires are banned on all forestland and at coastal beaches because of high fire danger. Officials were also concerned about an unusually high tide overnight Monday that could surprise eclipse enthusiasts who camp out on Oregon's beaches.
The weather is another unknown.
The forecast looks clear for Monday in Salem and central and eastern Oregon. But the coast — where the moon's shadow first makes landfall — may experience morning fog or early clouds.
That could send sky-gazers scrambling for a new viewing spot and further complicate an already difficult traffic mess, said Dave Thompson, a spokesman for the Oregon Department of Transportation.
Forty percent of Oregon-bound eclipse watchers are expected to be in place by Monday, but a recent Transportation Department survey reveals cause for concern.
About 11 percent of people headed to the central Oregon town of Madras, considered one of the nation's best viewing spots, were planning to arrive Monday morning. Thompson said it could take six hours or more to travel the roughly 50 miles (80 kilometers) from Portland to Salem on Sunday.
In Idaho, the path of totality will cross from the western town of Weiser to the community of Driggs on the eastern side of the state. Idaho officials there are warning travelers to keep gas tanks full and pack extra food and water in their vehicles. Local government officials have also been stocking up on rattlesnake venom.
Some experts have estimated that Idaho could see as many as 370,000 visitors for the eclipse. Weiser is expecting 20,000-plus visitors, a huge influx for a place that normally has just 5,500 residents.
To help the public, Oregon officials have activated a 211 phone number for updated information on traffic, weather and wildfires.
People hitting the roads can also check the state Transportation Department's TripCheck website for the latest on traffic. Oregon's Office of Emergency Management will be tweeting regular updates at @OregonOEM.