'Himachal Day', observed on 15 April, marks the date in 1948 when:

Himachal Day ("Himachal Diwas") is celebrated every year on 15 April to mark the formation of Himachal Pradesh on 15 April 1948.

History of Himachal Pradesh:

• On 15 April 1948, about 30 small princely states and hill estates in the Shimla Hills (such as Chamba, Mandi, Suket and Sirmaur) were merged to form Himachal Pradesh, a Chief Commissioner's province.
• In 1950, it became a "Part C" state under the Constitution.

In 1951, it got a Legislative Assembly, and Dr. Yashwant Singh Parmar became the first Chief Minister (1952).

In 1954, Bilaspur was merged with Himachal Pradesh.

On 1 November 1956, it became a Union Territory under the States Reorganisation Act.

On 1 November 1966, under the Punjab Reorganisation Act, the hill areas of Punjab (such as Kangra, Kullu, Lahaul and Spiti, and Shimla) were added to it.

On 25 January 1971, it became the 18th state of India under the State of Himachal Pradesh Act, 1970. This day is celebrated as "Purna Rajyatva Diwas" (Statehood Day).

Dr. Y. S. Parmar is called the "Architect of Himachal Pradesh".

About Himachal Pradesh:

• Capital: Shimla (summer); Dharamshala is the second (winter) capital (since 2017).
• Shimla was the summer capital of British India from 1864.

Famous places: Kullu, Manali, Dharamshala (McLeod Ganj, home of the Dalai Lama and the Tibetan government-in-exile), Spiti Valley and the Atal Tunnel (opened in 2020; at 9.02 km, the world's longest highway tunnel above 10,000 feet).

The Kalka-Shimla Railway is part of the Mountain Railways of India, a UNESCO World Heritage Site (2008).

The Great Himalayan National Park in Kullu is also a UNESCO World Heritage Site (2014).

It is known as "Dev Bhoomi" ("Land of the Gods") and the "Apple State of India".

Why not the other options?

• ✗Himachal Pradesh became a full state on 25 January 1971.
• ✗Shimla became the summer capital of British India in 1864.
• ✗Himachal Pradesh became a Union Territory on 1 November 1956.