Principal river of Nebraska. It is formed just east of the city of North Platte by the junction of the North Platte and South Platte rivers, and flows for 500 km/310 mi to join the Missouri River immediately above Plattsmouth, 25 km/16 mi south of Omaha. The three Platte rivers contain many dams for flood control and irrigation. They are unnavigable, but the western pioneer routes to the West, including the Oregon Trail and Mormon Trail, followed them in the mid-19th century. Later, the first transcontinental line, the Union Pacific Railroad, was laid along its course.
From its point of origin, the Platte runs southeast and then northeast, flowing in a wide arc past Kearney, Grand Island, and Columbus, where the Loup River, its largest tributary, enters it from the northwest. From Columbus, the river continues east to Fremont, and loops around the eastern and southern outskirts of Omaha on its way to the Missouri. Its drainage area of some 233,000 sq km/90,000 sq mi includes the Elkhorn River, which joins it west of Omaha. The river was named after the extremely flat area that surrounds it. It is too shallow and silted for navigation, but has long been used for irrigation. The total length of the Platte and the North Platte is 1,495 km/930 mi.