I would directly come to the parking problem which has become a major issue due to the increasing tourist visits. Definitely the places like Shimla, Manali, Mcleodganj have become congested.
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Editor India Study Channel.
You have rightly pointed out the menace caused by vehicles due to less or no parking space in the major areas. In the peak season huge pile up of vehicles is a common site in the places like Shimla, Manali and Mcleodganj as you said.
Apart from this local poulation is also increasing day by day and lot of buildings are being condtructed leading to more congestion in the hills.