The Swedish Armed Forces delivered food and water to up to 1,000 cars and trucks stuck in heavy snow for more than 24 hours.
Rescuers said they were working to free people stranded on the E22 main road in the Skane area in southern Sweden.
Many of those trapped were evacuated by rescue teams and asked to return to their cars later.
The travel chaos has occurred amid plummeting winter temperatures across the Nordic countries.
Extremely cold weather has hit parts of Sweden, Finland and Norway, and snowstorms in Denmark have left drivers stranded on a highway near Aarhus since Wednesday.
On Tuesday night, the Kvikkjokk-Arrenjarka meteorological station in northern Sweden recorded its coldest night in 25 years, with temperatures falling to -43.6 degrees Celsius.
The disruption on the main E22 route began at around 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 stopped amid the accumulated snow.
“It's complete chaos,” said police spokeswoman Evelina Olsson.
Snow plows arrived on Wednesday evening and police and rescue workers worked through the night to free hundreds of trapped cars. Some of them had medical problems, including diabetes.
Erika Sibilovit told the Aftonbladet website that she, her two children and her dog were released after 19 hours.
Malin Johansson, 56, from Ahus, said she and her partner were starting their car at regular intervals to keep it warm. She told Expressen newspaper that they were released when rescuers cut the central barrier of the road, allowing them to leave at 04:30 on Thursday.
Soldiers were sent to deliver food and water to the trapped people.
“The problem is that it snows so hard that the road is covered in snow just half an hour after it is plowed,” Ms. Olson said.
On Thursday morning, many cars were evacuated, although trucks were still stuck. Police said conditions were beginning to improve, but added that the road would not be cleared until 8:00 a.m. Friday at the earliest.
Buses and trains were canceled in the Skane area on Thursday morning and authorities urged people to avoid non-essential travel.
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