Omaha (pronounced /ˈoʊməhɑː/) is the largest city in the state of Nebraska, United States, and is the county seat of Douglas County. It is located in the Midwestern United States on the Missouri River, about 20 miles (30 km) north of the mouth of the Platte River. Omaha is the anchor of the Omaha-Council Bluffs metropolitan area, which includes Council Bluffs, Iowa, across the Missouri River from Omaha.

According to the 2010 Census, Omaha's population was 408,958, making it the nation's 42nd-largest city. Including its suburbs, Omaha formed the 60th-largest metropolitan area in the United States in 2010, with an estimated population of 877,110 residing in eight counties. There are more than 1.2 million residents within a 50-mile (80-km) radius of the city's center, forming the Greater Omaha area.

Omaha's pioneer period began in 1854 when the city was founded by speculators from neighboring Council Bluffs, Iowa. The city was founded along the Missouri River, and a crossing called Lone Tree Ferry earned the city its nickname, the "Gateway to the West." It introduced this new West to the world when in 1898 it played host to the World's Fair, dubbed the Trans-Mississippi Exposition. During the 19th century, Omaha's central location in the United States spurred the city to become an important national transportation hub. Throughout the rest of the 19th century, the transportation and jobbing sectors were important in the city, along with its railroads and breweries. In the 20th century, the Omaha Stockyards, once the world's largest, and its meatpacking plants, gained international prominence.