Most Koreans are on a five-day break right now for the traditional thanksgiving holiday, Chuseok.
Millions are on the nation's highways head to and from their ancestral hometowns where they'll spend time with family.
As of 4 PM, the trip by car from Seoul to the southeastern port city of Busan was taking around 4 hours and 50 minutes -- about an hour and a half longer than usual.
From Seoul to Gwangju it's about 3 and a half hours, and to the eastern coastal city of Gangneung about 2 hours and 50 minutes.
The highway authorities say they expect the roads will clear up at around 7 or 8 o'clock tonight.