More than 450 roads, including three national highways, have been blocked due to the recent snowfall in the higher reaches and tribal areas of Himachal Pradesh, officials said on Tuesday. The maximum 180 roads are blocked in Shimla, 150 in Lahaul and Spiti, 72 in Kinnaur, 35 in Kullu, 27 in Chamba, eight in Mandi and two each in Kangra and Sirmaur districts, they said, adding that in all 479 roads were blocked.