The city's population of 100,000 consists of the three Sikkimese ethnicities: the Bhutias, Lepchas, Nepalis as well as plainsmen from other states of India.

Within the higher peaks of the Himalayas and with a year-round mild temperate climate, Gangtok is at the centre of Sikkim's tourism industry.

In the early 20th century, Gangtok became a major stopover on the trade route between Lhasa in Tibet and cities such as Kolkata (then Calcutta) in British India.

In 1894, Thutob Namgyal, the Sikkimese monarch under British rule, shifted the capital from Tumlong to Gangtok, increasing the city's importance.

Sikkim came under the suzerainty of India, with the condition that it would retain its independence, by the treaty signed between the Chogyal and the then Indian Prime Minister Jawaharlal Nehru.

[12] In 1975, after years of political uncertainty and struggle, including riots, the monarchy was abrogated and Sikkim became India's twenty-second state, with Gangtok as its capital after a referendum.

[14] The town is on the side of a hill, with "The Ridge",[8][15] a promenade with the Raj Bhawan, the governor's residence, at one end and the palace, at an altitude of about 1,800 m (5,900 ft), at the other.

[16] Most of Sikkim, including Gangtok, is underlain by Precambrian rocks which contain foliated phyllites and schists; slopes are therefore prone to frequent landslides.

The existence of steep slopes, vulnerability to landslides, large forest cover and inadequate access to most areas have been a major impediment to the natural and balanced growth of the city.

The monsoon season from June to September is characterised by intense torrential rains, often causing landslides that block Gangtok's land access to the rest of the country.

Rainfall starts to rise from pre-monsoon in May and peaks during the monsoon, with July recording the highest monthly average of 649.6 mm (25.6 in).

[17] During this season the weather can be unstable and change abruptly from bright sunshine and clear skies to heavy rain within a couple of hours.

Gangtok's economy does not have a large manufacturing base, but has a thriving Cottage industry in watch-making, country-made alcohol and handicrafts.

The main market in Gangtok provides many of the state's rural residents a place to offer their produce during the harvest seasons.

As part of Sikkim, Gangtok enjoys the status of being an income-tax free region as per the state's 1948 Income tax law.

[13][32] These departments provide municipal functions such as garbage disposal, water supply, tax collection, licence allotments, and civic infrastructure.

Several roads in Gangtok are reported to be in a poor condition,[13] whereas building construction activities continue almost unrestrained in this city lacking proper land infrastructure.

[13] The main source of PHED water supply is the Rateychu River, located about 16 km (9.9 mi) from the city, at an altitude of 2,621 m (8,599 ft).

[13] Without a proper sanitation system, the practice of disposing sewage through septic tanks and directly discharging into Jhoras and open drains is prevalent.

The densely populated urban area of Gangtok does not have a combined drainage system to drain out the stormwater and wastewater from the buildings.

The highway also provides a link to the neighbouring hill station towns of Darjeeling and Kalimpong, which are the nearest urban areas.

There are quite many trains that connect Siliguri Junction with Sealdah railway station in Kolkata and others parts of north-east India.

Work has begun on a broad-gauge railway link from Sevoke in West Bengal to Rangpo in Sikkim,[44] which is planned for extension to Gangtok.

The quality of life, the pace of development and availability of basic infrastructure and employment prospects has been the major cause for rapid migration to the city.

Chotrul Duchen, Buddha Jayanti, the birthday of the Dalai Lama, Loosong, Bhumchu, Saga Dawa, Lhabab Duechen and Drupka Teshi are some other festivals, some distinct to local culture and others shared with the rest of India, Nepal, Bhutan and Tibet.

[24][64] A popular food in Gangtok is the momo,[65] a steamed dumpling containing pork, beef and vegetables cooked in a doughy wrapping and served with watery soup.

Thangka—a notable handicraft—is an elaborately hand-painted religious scroll in brilliant colours drawn on fabric hung in a monastery or a family altar and occasionally carried by monks in ceremonial processions.

[64] Chhaams are vividly costumed monastic dances performed on ceremonial and festive occasions, especially in the monasteries during the Tibetan new year.

Rumtek was the focus of international media attention in 2000 after the seventeenth Karmapa, one of the four holiest lamas, fled Lhasa and sought refuge in the monastery.

[83] BSNL, Vodafone, Jio and Airtel have the four largest cellular networks in the town with 4G services available within the city limits.