Agriculture has traditionally been the major feature of Sikkim's economy. Farming has been influenced by the nature of the terrain and by the diversity of climatic conditions. In Sikkimese agriculture attention is divided among staple cereal crops, commercial specialty crops, animals, and animal Products. Rice and corn lead in hectares planted, but cardamom, citrus fruits, apples, and pineapples enter trade channels and so are better known. Potatoes are the major cash crop. Sheep, goats, cattle, yaks, and mules are abundant. The animals support the population in the high mountain valleys. The pastoral industries furnish wool, skins, hides, and surplus commodities.
About one-third of Sikkim's 7,096 square kilometers of mountainous territory is forested. Forests are considered one of the kingdom's greatest assets. There are valuable plantations of sal ( Shorea robusta, a common timber tree that is a source of inexpensive building materials), sisal (a source of cordage), and bamboo. Since the 1960s Sikkim's mining corporation has been instrumental in sponsoring systematic mineral development. Copper, lead, and zinc are mined in large quantities. In Sikkim's forests there are raw materials for manufacture of paper pulp, matches, furniture, packing boxes, and tea chests. Sikkim's development has been severely slowed down by the lack of power supplies.
A major strategic road was built by the Indian army engineers and India's Border Road Development Board. This road is 240 kilometers long and is called the North Sikkim Highway. The highway that connects Gangtok with the northern border areas was completed in 1962 by India. Construction work on the road started in 1958, but several factors slowed the project. Besides the engineering problems, one of the main difficulties was supplying food for such a large labor force: there were about 6,000 workers during peak periods.