The Swedish armed forces have delivered food and water to up to 1,000 cars and lorries stuck in heavy snow for nearly 24 hours.
Rescuers said they were working to free people stuck on the main E22 road in the Skane area of southern Sweden.
Many of those trapped were evacuated by rescue teams and told to return to their cars later.
The travel chaos occurred amid plummeting winter temperatures across the Nordic countries.
Extreme cold weather has hit parts of Sweden, Finland and Norway, and snow storms in Denmark have left drivers trapped on a motorway near Aarhus since Wednesday.
The Kvikkjokk-Arrenjarka weather station in northern Sweden recorded its coldest night for 25 years on Tuesday night, with temperatures dropping to -43.6C.
The disruption on the main E22 began at about 09:00 local time (08:00 GMT) on Wednesday when snow made the E22 impassable in both directions between Horby and Kristianstad. Hundreds of cars ground to a halt in snowdrifts.
"It is total chaos," police spokesperson Evelina Olsson said.
Snow ploughs arrived on Wednesday evening and police and rescuers worked through the night to free people in the hundreds of trapped cars. Some had medical issues, including diabetes.
Erika Sepeliovaite told Aftonbladet website that she and her two children and her dog were freed after 19 hours.
Malin Johansson, 56, from Ahus, said she and her partner had started their car at regular intervals to keep it warm. She told Expressen they were freed when rescuers cut the road's central barrier, allowing them to leave at 04:30 on Thursday.
Soldiers were dispatched to deliver food and water to the people trapped.
"The problem is that it is snowing so heavily that the road is covered in snow just half an hour after ploughing," Ms Olsson said.
On Thursday morning many of the cars had been cleared, although lorries were still stuck. Police said conditions were beginning to improve but added that the road would not be cleared until 08:00 on Friday at the earliest.
Buses and trains were cancelled in the Skane region on Thursday morning and authorities urged people to avoid unessential travel.
