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Yes, you can easily reach Himachal Pradesh by bus from various cities. Major destinations like Delhi, Chandigarh, and Jaipur are connected to different places in Himachal through inter state bus services. Government and private operators provide services on a regular basis and offer standard buses to luxury buses.
Travel time depends on the starting point and destination. From Delhi to popular towns like Shimla or Manali, it would take around 8 to 12 hours, and from Chandigarh, it takes approximately 4 to 8 hours.
For those who need more flexibility, think about Bus on rent in Delhi for Himachal. By this, you will fix up your itinerary and drive in a group at your own pace. Many operators have such facilities with different sizes of vehicles to accommodate groups of all sizes and budgets.
The reason is that it is easily approachable to the neighbouring states due to a well laid out journey across the network of roads, with main entry points from Chandigarh, Kalka and Pathankot.