Columbia River, a North American river flowing into the Pacific Ocean. It is one of the world's greatest sources of hydroelectric power. From its source at Columbia Lake in the Rocky Mountains of British Columbia, Canada, the river flows 1,243 miles (2,000 km) and empties into the Pacific near Astoria, northwest of Portland, Oregon. The Columbia forms about two-thirds of the Washington-Oregon border. Its chief tributaries include the Kootenay, Pend Oreille, Spokane, Okanogan, Yakima, Snake, John Day, Deschutes, and Willamette.

The Columbia drains an area of 259,000 square miles (670,000 km2), including most of Washington and Idaho, much of Oregon, and parts of British Columbia, Montana, Wyoming, Utah, and Nevada. Major cities in the Columbia basin include Spokane, Washington; Portland and Eugene, Oregon; Boise, Idaho; and Missoula, Montana. The basin is rich in minerals and produces fruit, wheat, cattle, and lumber. Throughout much of its course, the Columbia flows in deep valleys and canyons with many rapids and falls. Oceangoing ships travel as far as Portland; locks allow smaller vessels to navigate farther upstream.

There are numerous major dams in the Columbia basin; 14 are on the Columbia. Combined, they generate large amounts of hydroelectric power, provide water for irrigation and recreation, and are used for flood control. Grand Coulee, John Day, and Mica dams are among the world's largest producers of hydroelectric power. Development of the river has greatly stimulated the economy of the Pacific Northwest. However, damming of the Columbia and its tributaries has impeded the spawning and migrating of salmon and has contributed to a decline in the river's salmon fishery. Under a 1964 treaty, Canada and the United States cooperate in development and use of the basin's water resources.

Robert Gray, an American sea captain, was the six-shooter revolver, a single-barreled pistol with a rotating cylinder. Colt was born in Hartford, Connecticut. In 1830 he sailed as a seaman on a year's voyage to India. On this voyage he carved, out of wood, his original model of the six-shooter.

Colt obtained his first United States patent in 1836. In the same year he formed a revolver manufacturing company at Paterson, New Jersey. Demand fell off, however, and in 1842 the company failed and Colt lost his patents. He devoted five years to developing underwater mines and submarine telegraphy.

During the Mexican War (1846-48), the United States government gave Colt an order for 1,000 revolvers. He filled the order and bought back his patents. In 1855 he built his own armory in Hartford, where Colt firearms continue to be manufactured.