Various Native American tribes had lived in the land that became Omaha, including since the 17th century, the Omaha and Ponca, Dhegian-Siouan-language people who had originated in the lower Ohio River valley and migrated west by the early 17th century; Pawnee, Otoe, Missouri, and Ioway. The word Omaha (actually Umoⁿhoⁿ or Umaⁿhaⁿ) means "Dwellers on the bluff".

In 1804 the Lewis and Clark Expedition passed the riverbanks where the city of Omaha would be built. Between July 30 and August 3, 1804, members of the expedition, including Meriwether Lewis and William Clark, met with Oto and Missouria tribal leaders at the Council Bluff at a point about 20 miles (32 kilometers) north of present-day Omaha. Immediately south of that area, Americans built several fur trading outposts in succeeding years, including Fort Lisa in 1812;Fort Atkinson in 1819;Cabanné's Trading Post, built in 1822, and Fontenelle's Post in 1823, in what became Bellevue. There was fierce competition among fur traders until John Jacob Astor created the monopoly of the American Fur Company. The Mormons built a town called Cutler's Park in the area in 1846. While it was temporary, the settlement provided the basis for further development.

Through 26 separate treaties with the United States federal government, Native American tribes in Nebraska gradually ceded the lands that now make up the state. The treaty and cession involving the Omaha area occurred in 1854 when the Omaha Tribe ceded most of east-central Nebraska.Logan Fontenelle, an interpreter for the Omaha and signatory to the 1854 treaty, played an essential role in those proceedings.

Before it was legal to claim land in Indian Country, William D. Brown operated the Lone Tree Ferry that brought settlers from Council Bluffs, Iowa to the area that became Omaha. Brown is generally credited as having the first vision for a city where Omaha now sits. The passage of the Kansas–Nebraska Act in 1854 was presaged by the staking out of claims around the area to become Omaha by residents from neighboring Council Bluffs. On July 4, 1854, the city was informally established at a picnic on Capital Hill, current site of Omaha Central High School. Soon after, the Omaha Claim Club was formed to provide vigilante justice for claim jumpers and others who infringed on the land of many of the city's founding fathers. Some of this land, which now wraps around Downtown Omaha, was later used to entice Nebraska Territorial legislators to an area called Scriptown. The Territorial capitol was in Omaha, but when Nebraska became a state in 1867, the capital was relocated to Lincoln, 53 miles (85 km) south-west of Omaha. The U.S. Supreme Court later ruled against numerous landowners whose violent actions were condemned in Baker v. Morton.

Many of Omaha's founding figures stayed at the Douglas House or the Cozzens House Hotel.Dodge Street was important early in the city's early commercial history; North 24th Street and South 24th Street also developed independently as business districts. Early pioneers were buried in Prospect Hill Cemetery and Cedar Hill Cemetery. Cedar Hill closed in the 1860s and its graves were moved to Prospect Hill, where pioneers were later joined by soldiers from Fort Omaha, African Americans and early European immigrants. There are several other historical cemeteries in Omaha, historical Jewish synagogues and historical Christian churches dating from the pioneer era, as well. Two sculpture parks, Pioneer Courage and Spirit of Nebraska's Wilderness and The Transcontinental Railroad, celebrate the city's pioneering history.

The economy of Omaha boomed and busted through its early years. In 1858, the Omaha Daily Republican was founded by the Omaha Printing Company (rebranded Aradius Group, 2016), it was Nebraska's first regional newspaper–founded before Nebraska claimed statehood. Omaha was a stopping point for settlers and prospectors heading west, either overland or by the Missouri River. The steamboat Bertrand sank north of Omaha on its way to the goldfields in 1865. Its massive collection of artifacts is on display at the nearby Desoto National Wildlife Refuge. The jobbing and wholesaling district brought new jobs, followed by the railroads and the stockyards. Groundbreaking for the First Transcontinental Railroad in 1863, provided an essential developmental boom for the city. In 1862, the U.S. Congress allowed the Union Pacific Railroad to begin building westward railways; in January 1866 it commenced construction out of Omaha.

The Union Stockyards, another important part of the city's development, were founded in South Omaha in 1883. Within 20 years, Omaha had four of the five major meatpacking companies in the United States. By the 1950s, half the city's workforce was employed in meatpacking and processing. Meatpacking, jobbing and railroads were responsible for most of the growth in the city from the late 19th century through the early decades of the 20th century.

Immigrants soon created ethnic enclaves throughout the city, including Irish in Sheelytown in South Omaha; Germans in the Near North Side, joined by the European Jews and black migrants from the South; Little Italy and Little Bohemia in South Omaha. Beginning in the late 19th century, Omaha's upper class lived in posh enclaves throughout the city, including the south and north Gold Coast neighborhoods, Bemis Park, Kountze Place, Field Club and throughout Midtown Omaha. They traveled the city's sprawling park system on boulevards designed by renowned landscape architect Horace Cleveland. The Omaha Horse Railway first carried passengers throughout the city, as did the later Omaha Cable Tramway Company and several similar companies. In 1888, the Omaha and Council Bluffs Railway and Bridge Company built the Douglas Street Bridge, the first pedestrian and wagon bridge between Omaha and Council Bluffs.

Gambling, drinking and prostitution were widespread in the 19th century, first rampant in the city's Burnt District and later in the Sporting District. Controlled by Omaha's political boss Tom Dennison by 1890, criminal elements enjoyed support from Omaha's "perpetual" mayor, "Cowboy Jim" Dahlman, nicknamed for his eight terms as mayor.

Calamities such as the Great Flood of 1881 did not slow down the city's violence. In 1882, the Camp Dump Strike pitted state militia against unionized strikers, drawing national attention to Omaha's labor troubles. The Governor of Nebraska had to call in U.S. Army troops from nearby Fort Omaha to protect strikebreakers for the Burlington Railroad, bringing along Gatling guns and a cannon for defense. When the event ended, one man was dead and several were wounded. In 1891, a mob hanged Joe Coe, an African-American porter after he was accused of raping a white girl. There were also several other riots and civil unrest events in Omaha during this period.

In 1898, Omaha's leaders, under the guidance of Gurdon Wattles, held the Trans-Mississippi and International Exposition, touted as a celebration of agricultural and industrial growth throughout the Midwest. The Indian Congress, which drew more than 500 American Indians from across the country, was held simultaneously. More than 2 million visitors attended these events at Kountze Park and the Omaha Driving Park in the Kountze Place neighborhood.

With dramatically increasing population in the 20th century, competition and fierce labor struggles led to major civil unrest. In 1900, Omaha was the center of a national uproar over the kidnapping of Edward Cudahy, Jr., the son of a local meatpacking magnate.

The city's labor and management clashed in bitter strikes, racial tension escalated as Blacks were hired as strikebreakers, and ethnic strife broke out. A major riot by earlier immigrants in South Omaha destroyed the city's Greek Town in 1909, completely driving out the Greek population.

The civil rights movement in Omaha has roots that extend back to 1912, when the first chapter of the National Association for the Advancement of Colored People west of the Mississippi River was founded in the city.

The Omaha Easter Sunday Tornado of 1913 destroyed much of the city's African-American community, in addition to much of Midtown Omaha.

Six years later, in 1919, the city was caught up in the Red Summer riots when thousands of whites marched from South Omaha to the courthouse to lynch a Black worker, Willy Brown, a suspect in an alleged rape of a white woman. The mob burned the Douglas County Courthouse to get the prisoner, causing more than $1 million damage. They hanged and shot Will Brown, then burned his body. Troops were called in from Fort Omaha to quell the riot, prevent more crowds gathering in South Omaha, and to protect the Black community in North Omaha.

The culture of North Omaha thrived throughout the 1920s through 1950s, with several creative figures, including Tillie Olsen, Wallace Thurman, Lloyd Hunter, and Anna Mae Winburn emerging from the vibrant Near North Side.

Musicians created their own world in Omaha, and also joined national bands and groups that toured and appeared in the city.

After the tumultuous Great Depression of the 1930s, Omaha rebounded with the development of Offutt Air Force Base just south of the city. The Glenn L. Martin Company operated a factory there in the 1940s that produced 521 B-29 Superfortresses, including the Enola Gay and Bockscar used in the atomic bombing of Japan in World War II.

The construction of Interstates 80, 480 and 680, along with the North Omaha Freeway, spurred development. There was also controversy, particularly in North Omaha, where new routes bisected several neighborhoods.Creighton University hosted the DePorres Club, an early civil rights group whose use of sit-in strategies for integration of public facilities predated the national movement.

Following the development of the Glenn L. Martin Company bomber manufacturing plant in Bellevue at the beginning of World War II, the relocation of the Strategic Air Command to the Omaha suburb in 1948 provided a major economic boost to the area.

From the 1950s through the 1960s, more than 40 insurance companies were headquartered in Omaha, including Woodmen of the World and Mutual of Omaha. By the late 1960s, the city rivaled, but never surpassed, the United States insurance centers of Hartford, Connecticut, New York City and Boston.

After surpassing Chicago in meat processing by the late 1950s, Omaha suffered the loss of 10,000 jobs as both the railroad and meatpacking industries restructured. The city struggled for decades to shift its economy as workers suffered. Poverty became more entrenched among families who remained in North Omaha.

In the 1960s, three major race riots along North 24th Street destroyed the Near North Side's economic base, with recovery slow for decades. In 1969, Woodmen Tower was completed and became Omaha's tallest building and first major skyscraper at 478 feet (146 m), a sign of renewal.

Since the 1970s, Omaha has continued expanding and growing, mostly to available land to the west. West Omaha has become home to the majority of the city's population. North and South Omaha's populations continue to be centers of new immigrants, with economic and racial diversity. In 1975 a major tornado, along with a major blizzard, caused more than $100 million in damages in 1975 dollars.

Downtown Omaha has since been rejuvenated in numerous ways, starting with the development of Gene Leahy Mall and W. Dale Clark Library in the late 1970s. In the 1980s, Omaha's fruit warehouses were converted into a shopping area called the Old Market.

The demolition of Jobber's Canyon in 1989 led to the creation of the ConAgra Foods campus. Several nearby buildings, including the Nash Block, have been converted into condominiums. The stockyards were taken down; the only surviving building is the Livestock Exchange Building, which was converted to multi-use and listed on the National Register of Historic Places.

A historic preservation movement in Omaha has led to a number of historic structures and districts being designated Omaha Landmarks or listed on the National Register of Historic Places. Much of the push toward preservation came after Omaha gained the notorious designation of having, in 1989, demolished the largest-ever National Register historic district in the United States, a record that still stands as of 2013. The Jobbers Canyon Historic District, along the Missouri River, was felled for a new headquarters campus for ConAgra Foods, a company which threatened to relocate if Omaha did not allow them to raze the city's historic district. The Jobber's Canyon warehouses had before then been allowed to deteriorate and were the scene of several fires set by the homeless population that had come to live in the abandoned buildings. At the time, there were no plans in place for revitalizing the buildings.

In the 1980s and 1990s, Omaha also saw major company headquarters leave the city, including Enron, founded in the city in 1930 and taken to Houston in 1987 by the now-notorious Kenneth Lay. First Data Corporation, a large credit-card processor, also was founded in Omaha in 1969; as of 2009, its headquarters are in Atlanta.

Inacom, founded in Omaha in 1991, was a technology company that customized computer systems for large businesses, and was on the Fortune 500 list from 1997 until 2000, when it filed for bankruptcy. Northwestern Bell, the Bell System affiliate for Northwestern states, had its headquarters in Omaha from its founding in 1896 until it moved to Denver in 1991 as US West. Level 3 Communications, a large Tier 1 network provider, was founded in Omaha in 1985 as Kiewit Diversified Group, a division of Kiewit Corporation, a Fortune 500 construction and mining company still headquartered in Omaha; Level 3 moved to Denver in 1998. World Com was founded by a merger with Omaha's MFS Communications, started as Metropolitan Fiber Systems in 1993. MFS, backed by Kiewit Corporation CEO Walter Scott and Warren Buffett, purchased UUNET, one of the largest Internet backbones in the world, for $2 billion in 1996. The now-infamous Bernie Ebbers purchased the much larger MFS for $14.3 billion in 1997 under his World Com. He moved headquarters of the merged company from Omaha to Mississippi.

Around the start of the 21st century, several new downtown skyscrapers and cultural institutions were built.One First National Center was completed in 2002, surpassing the Woodmen Tower as the tallest building in Omaha as well as in the state at 634 feet (193 m). The creation of the city's new North Downtown included the construction of the CenturyLink Center and the Slowdown/Film Streams development at North 14th and Webster Streets. Construction of the new TD Ameritrade Park began in 2009 and was completed in 2011, also in the North Downtown area, near the CenturyLink Center. TD Ameritrade Park is now the home of the College World Series, an event tourists flock to each year.

New construction has occurred throughout the city since the start of the 21st century. Important retail and office developments have occurred in West Omaha such as the Village Pointe shopping center and several business parks including First National Business Park and parks for Bank of the West and C&A Industries, Inc and Morgan Stanley Smith Barney and several others. Downtown and Midtown Omaha have both seen the development of a significant number of condominiums in recent years. In Midtown Omaha significant mixed-use projects are underway. The site of the former Ak-Sar-Ben arena has been redeveloped into a mixed-use development Aksarben Village. In January 2009 Blue Cross Blue Shield of Nebraska announced plans to build a new 10 story, $98 million headquarters, in the Aksarben Village, completed in Spring 2011.Gordmans is also building their new corporate headquarters in Aksarben. The other major mixed-use development is Midtown Crossing at Turner Park. Developed by Mutual of Omaha, the development includes several condominium towers and retail businesses built around Omaha's Turner Park.

The Holland Performing Arts Center opened in 2005 near the Gene Leahy Mall and the Union Pacific Center opened in 2004.

There have also been several developments along the Missouri River waterfront in downtown. The Bob Kerrey Pedestrian Bridge was opened to foot and bicycle traffic on September 28, 2008. Started in 2003,RiverFront Place Condos first phase was completed in 2006 and is fully occupied and the second phase was opened in 2011. The development along Omaha's riverfront is attributed with prompting the City of Council Bluffs to move their own riverfront development time line forward.

In the summers of 2008, 2012 and 2016 the United States Olympic Team swimming trials were held in Omaha, at the Qwest/Century Link Center. The event was a highlight in the city's sports community, as well as a showcase for redevelopment in the downtown area.

As of the census of 2010, there were 408,958 people, 162,627 households, and 96,477 families residing in the city. The population density was 3,217.9 inhabitants per square mile (1,242.4/km²). There were 177,518 housing units at an average density of 1,396.8 per square mile (539.3/km²). The city's racial makeup was 73.1% White, 13.7% African American, 0.8% Native American, 2.4% Asian, 0.1% Pacific Islander, 6.9% from other races, and 3.0% from two or more races. Hispanic or Latino people of any race were 13.1% of the population. Non-Hispanic Whites were 68.0% of the population.

There were 162,627 households, of which 31.3% had children under the age of 18 living with them, 40.6% were married couples living together, 13.7% had a female householder with no husband present, 4.9% had a male householder with no wife present, and 40.7% were non-families. 32.3% of all households were made up of individuals, and 9.3% had someone living alone who was at least 65 years old. The average household size was 2.45 and the average family size was 3.14.

The median age in the city was 33.5 years. 25.1% of residents were under the age of 18; 11.4% were between the ages of 18 and 24; 27.9% were from 25 to 44; 24.4% were from 45 to 64; and 11.4% were 65 years of age or older. The city's gender makeup was 49.2% male and 50.8% female.

The median household income (in 2017 dollars) from 2013 to 2017 was $53,789.

As of the census of 2000, there were 390,007 people, 156,738 households, and 94,983 families residing within city limits. The population density was 3,370.7 people per square mile (1,301.5/km²). There were 165,731 housing units at an average density of 1,432.4 per square mile (553.1/km²). The city's racial makeup was 78.4% White, 13.3% African American, 0.7% Native American, 1.7% Asian, 0.1% Pacific Islander, 3.9% from other races, and 1.9% from two or more races. Hispanic or Latino of any race were 7.5% of the population.

The city's median household income was $40,006, and the median family income was $50,821. Males had a median income of $34,301 versus $26,652 for females. The city's per capita income was $21,756. About 11.3% of the population and 7.8% of families were below the poverty line, including 15.6% of those under the age of 18 and 7.4% of those 65 and older.

Native Americans were the first residents of the Omaha area. The city of Omaha was established by white settlers from neighboring Council Bluffs who arrived from the Northeast United States a few years earlier. While much of the early population was of Yankee stock, over the next 100 years numerous ethnic groups moved to the city. In 1910, the Census Bureau reported Omaha's population as 96.4% White and 3.6% Black.Irish immigrants in Omaha originally moved to an area in present-day North Omaha called "Gophertown", as they lived in dug-out sod houses. That population was followed by Polish immigrants in the Sheelytown neighborhood, and many immigrants were recruited for jobs in South Omaha's stockyards and meatpacking industry. The German community in Omaha was largely responsible for founding its once-thriving beer industry, including the Metz, Krug, Falstaff and the Storz breweries.

Since its founding, ethnic groups in the city have clustered in enclaves in north, south and downtown Omaha. In its early days, the sometimes lawless nature of a new frontier city included crime, such as illicit gambling and riots.

In the early 20th century, Jewish immigrants set up many businesses along the North 24th Street commercial area. It suffered with the loss of industrial jobs in the 1960s and later, the shifting of population west of the city. The commercial area is now the center of the African-Americans community, concentrated in North Omaha. The African American community has maintained its social and religious base, while it is experiencing an economic revitalization.

The Little Italy neighborhood grew south of downtown, as many Italian immigrants came to the city to work in the Union Pacific shops. Scandinavians first came to Omaha as Mormon settlers in the Florence neighborhood.Czechs had a strong political and cultural voice in Omaha, and were involved in a variety of trades and businesses, including banks, wholesale houses, and funeral homes. The Notre Dame Academy and Convent and Czechoslovak Museum are legacies of their residence. Today the legacy of the city's early European immigrant populations is evident in many social and cultural institutions in Downtown and South Omaha.

Mexicans originally immigrated to Omaha to work in the rail yards. Today they account for most of South Omaha's Hispanic population and many have taken jobs in meat processing. Other large early ethnic populations in Omaha included Danes, Poles, and Swedes.

A growing number of African immigrants have made their homes in Omaha in the last twenty years.^[when?] There are approximately 8,500 Sudanese living in Omaha, including the largest population of Sudanese refugees in the United States. Most have immigrated since 1995 because of warfare in Sudan. They represent ten ethnic groups, including the Nuer, Dinka, Equatorians, Maubans and Nubians. Most Sudanese people in Omaha speak the Nuer language. Other Africans have immigrated to Omaha as well, with one-third from Nigeria, and large populations from Kenya, Togo, Cameroon and Ghana.

With the expansion of railroad and industrial jobs in meatpacking, Omaha attracted many immigrants and migrants. As the major city in Nebraska, it has historically been more racially and ethnically diverse than the rest of the state. At times rapid population change, overcrowded housing and job competition have aroused racial and ethnic tensions. Around the start of the 20th century, violence towards new immigrants in Omaha often erupted out of suspicion and fear.

In 1909, anti-Greek sentiment flared after increased Greek immigration, and worsened their tendency to become strikebreakers. The killing of a policeman of Irish descent enraged the Irish community; an angry mob violently stormed the Greek neighborhood in Omaha in what would become known as the Greek Town Riot. That mob violence forced the Greek immigrant population to flee from the city. By 1910, 53.7% of Omaha's residents and 64.2% of South Omaha's residents were foreign born or had at least one parent born outside of America.

Six years after the Greek Town Riot, in 1915, a mob killed Juan Gonzalez, a Mexican immigrant, near Scribner, a town in the Greater Omaha metropolitan area. The event occurred after an Omaha Police Department officer investigated a criminal operation that sold goods stolen from the nearby railroad yards. Racial profiling targeted Gonzalez as the culprit. After escaping the city, he was trapped along the Elkhorn River, where the mob, including several policemen from Omaha, shot him more than twenty times. It was discovered Gonzalez was unarmed, and he had a reliable alibi for the time of the murder. No one was ever indicted for his killing.

In the fall of 1919, following Red Summer, postwar social and economic tensions, the earlier hiring of African Americans as strikebreakers, and job uncertainty contributed to a mob from South Omaha lynching Willy Brown and the ensuing Omaha Race Riot. Trying to defend Brown, the city's mayor, Edward Parsons Smith, was lynched also, surviving only after a quick rescue.

Like other industrial cities in the U.S., Omaha suffered severe job losses in the 1950s, more than 10,000 in all, as the railroad and meatpacking industries restructured. Stockyards and packing plants were located closer to ranches, and union achievements were lost as wages declined in surviving jobs. Many workers left the area if they could get to other jobs. Poverty deepened in areas of the city whose residents depended on those jobs, specifically North and South Omaha. At the same time, with reduced revenues, the city had less financial ability to respond to longstanding problems.

Despair after the April 1968 assassination of Martin Luther King Jr. contributed to riots in North Omaha, including one at the Logan Fontenelle Housing Project. For some, the civil rights movement in Omaha, Nebraska evolved towards black nationalism, as the Black Panther Party was involved in tensions in the late 1960s. Organizations such as the Black Association for Nationalism Through Unity became popular among the city's African-American youth. This tension culminated in the cause célèbre trial of the Rice/Poindexter Case, in which an Omaha Police Department officer was killed by a bomb while answering an emergency call.

Whites in Omaha have followed the white flight pattern, suburbanizing to West Omaha. In the late 1990s and early 2000s, gang violence and incidents between the Omaha Police and Black residents undermined relations between groups in North and South Omaha.