Although traffic to areas within the path of totality was somewhat spread out over the days prior to the eclipse, there were widespread traffic problems across the United States after the event ended.
Michael Zeiler, an eclipse cartographer, had estimated that between 1.85 million and 7.4 million people would travel to the path of the eclipse.

In Oregon, because an estimated one million people were expected to arrive, the Oregon National Guard was called in to help manage traffic in Madras along US 26 and US 97.
Madras Municipal Airport received more than 400 mostly personal planes that queued for hours while waiting to leave after the eclipse.

Officials in Idaho, where the totality path crossed the center of the state, began planning for the eclipse a year in advance.
The state Transportation Department suspended construction projects along Interstate 15, which traverses Eastern Idaho, from August 18–22 in order to have all lanes open; their counterparts in neighboring Utah, where many were expected to travel the 220 miles (350 km) north via the highway from the Salt Lake City metropolitan area, did the same.
On the morning of the eclipse, many drivers left before dawn, creating traffic volume along I-15 normally not seen until morning rush hour; northbound traffic on the interstate in Box Elder County north of Salt Lake City slowed to 10–15 miles per hour (16–24 km/h).
The Idaho State Police (ISP) stationed a patrol car along I-15 every 15 miles (24 km) between Shelley and the Utah border.

After the eclipse, traffic more than doubled along I-15 southbound, with extensive traffic jams continuing for eight hours as viewers who had traveled north into the totality path from Utah returned there and to points south.
The ISP tweeted a picture of bumper-to-bumper traffic stalled on the interstate just south of Idaho Falls.
Motorists reported to local news outlets that it was taking them two hours to travel the 47 miles (76 km) from that city to Pocatello to the south, a journey that normally takes 45 minutes.
Others reported that it took three hours to travel from Idaho Falls to the closer city of Blackfoot, 30 miles (48 km) farther north of Pocatello.

In the rest of the state the impact was less severe.
Traffic nearly doubled on US 93, and was up 55 percent on US 20.

For some northbound travelers on I-15, the Montana Department of Transportation had failed to make similar plans to those in Idaho, scheduling a road construction project to begin on August 21 that narrowed a section of the highway to a single northbound lane, near the exit to Clark Canyon Dam south of Dillon.
Though that stretch of highway generally has a traffic count of less than 1,000 vehicles per day, on the day of the eclipse there were over a thousand vehicles per hour at peak times.
As a result, traffic backed up as far as Lima, creating a delay of at least an hour for travelers heading northward.
Further, as construction had not yet begun, drivers observed cones set up but no workers present on the road.
While the state traditionally halts construction projects during high traffic periods, a state official admitted "we ... probably made a bad mistake here in this regard."

In Wyoming, estimates were that the population of the state, officially 585,000, may have doubled or even tripled, with traffic counts on August 21 showing 536,000 more cars than the five-year average for the third Monday in August; a 68 percent increase.
One official offered an estimate of "two people in every car" to arrive at a one-million-visitor figure, and others noted that one million was a conservative estimate based on a one-day traffic count of limited portions of major highways.
 There were additional arrivals by aircraft, plus travelers who arrived early or stayed for additional days.
Two days before the eclipse, traffic increased 18 percent over a five-year average, with an additional 131,000 vehicles on the road.
Sunday saw an additional 217,000-vehicle increase.

Following the eclipse, more than 500,000 vehicles traveled Wyoming roads, creating large traffic jams, particu
Although traffic to areas within the path of totality was somewhat spread out over the days prior to the eclipse, there were widespread traffic problems across the United States after the event ended. Michael Zeiler, an eclipse cartographer, had estimated that between 1.85 million and 7.4 million people would travel to the path of the eclipse.
In Oregon, because an estimated one million people were expected to arrive, the Oregon National Guard was called in to help manage traffic in Madras along US 26 and US 97. Madras Municipal Airport received more than 400 mostly personal planes that queued for hours while waiting to leave after the eclipse.
Officials in Idaho, where the totality path crossed the center of the state, began planning for the eclipse a year in advance. The state Transportation Department suspended construction projects along Interstate 15, which traverses Eastern Idaho, from August 18–22 in order to have all lanes open; their counterparts in neighboring Utah, where many were expected to travel the 220 miles (350 km) north via the highway from the Salt Lake City metropolitan area, did the same. On the morning of the eclipse, many drivers left before dawn, creating traffic volume along I-15 normally not seen until morning rush hour; northbound traffic on the interstate in Box Elder County north of Salt Lake City slowed to 10–15 miles per hour (16–24 km/h). The Idaho State Police (ISP) stationed a patrol car along I-15 every 15 miles (24 km) between Shelley and the Utah border.
After the eclipse, traffic more than doubled along I-15 southbound, with extensive traffic jams continuing for eight hours as viewers who had traveled north into the totality path from Utah returned there and to points south. The ISP tweeted a picture of bumper-to-bumper traffic stalled on the interstate just south of Idaho Falls. Motorists reported to local news outlets that it was taking them two hours to travel the 47 miles (76 km) from that city to Pocatello to the south, a journey that normally takes 45 minutes. Others reported that it took three hours to travel from Idaho Falls to the closer city of Blackfoot, 30 miles (48 km) farther north of Pocatello.
In the rest of the state the impact was less severe. Traffic nearly doubled on US 93, and was up 55 percent on US 20.
For some northbound travelers on I-15, the Montana Department of Transportation had failed to make similar plans to those in Idaho, scheduling a road construction project to begin on August 21 that narrowed a section of the highway to a single northbound lane, near the exit to Clark Canyon Dam south of Dillon. Though that stretch of highway generally has a traffic count of less than 1,000 vehicles per day, on the day of the eclipse there were over a thousand vehicles per hour at peak times. As a result, traffic backed up as far as Lima, creating a delay of at least an hour for travelers heading northward. Further, as construction had not yet begun, drivers observed cones set up but no workers present on the road. While the state traditionally halts construction projects during high traffic periods, a state official admitted "we ... probably made a bad mistake here in this regard."
In Wyoming, estimates were that the population of the state, officially 585,000, may have doubled or even tripled, with traffic counts on August 21 showing 536,000 more cars than the five-year average for the third Monday in August; a 68 percent increase. One official offered an estimate of "two people in every car" to arrive at a one-million-visitor figure, and others noted that one million was a conservative estimate based on a one-day traffic count of limited portions of major highways.  There were additional arrivals by aircraft, plus travelers who arrived early or stayed for additional days. Two days before the eclipse, traffic increased 18 percent over a five-year average, with an additional 131,000 vehicles on the road. Sunday saw an additional 217,000-vehicle increase.
Following the eclipse, more than 500,000 vehicles traveled Wyoming roads, creating large traffic jams, particu
Solar eclipse of August 21, 2017