control of external affairs on behalf of Sikkimese. Trade between India and Tibet flourished through the Nathula and Jelepla passes, benefiting Gangtok. Trade declined with the Chinese crackdown in Tibet in 1959 and the passes were sealed after the Sino-Indian War in 1962. The Nathula pass was finally opened to limited trade in 2006, fuelling hopes of economic boom. 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. Gangtok has witnessed annual landslides, resulting in loss of life and damage to property. The largest disaster occurred in June 1997, when 38 were killed and hundreds of buildings were destroyed. Geography Gangtok is located at (coordinates of Gangtok head post office). It is in the lower Himalayas at an elevation of . The town is on the side of a hill, with "The Ridge", a promenade with the Raj Bhawan, the governor's residence, at one end and the palace, at an altitude of about , at the other. The city is flanked east and west by two streams, Roro Chu and Ranikhola. These two rivers divide the natural drainage into two parts, eastern and western. Both streams meet the Ranipul and flow south as the Ranikhola before joining the Teesta at Singtam. Most kind roads are steep, with the buildings built on compacted ground alongside them. Most of Sikkim, including Gangtok, is underlain by Precambrian rocks which contain foliated phyllites and schists; slopes are therefore prone to frequent landslides. Surface runoff of water by natural streams (jhora) and man-made drains has contributed to the risk of landslides. According to the Bureau of Indian Standards, the town falls under seismic zone-IV (on a scale of I to V, in order of increasing seismic activity), near the convergent boundary of the Indian and the Eurasian tectonic plates and is subject to frequent earthquakes. The hills are nestled within higher peaks and the snow-clad Himalayan ranges tower over the town in the distance. Mount Kanchenjunga (8,598 m or 28,208 ft)—the world's third-highest peak—is visible to the west of the city. 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. Densely forested regions surround Gangtok, temperate, deciduous forests of poplar, birch, oak and