Atlanta is the capital and the most populous city of the state of Georgia, and the core city of the ninth most populous metropolitan area in the United States. It is the county seat of Fulton County, although portions of the city extend into DeKalb County. As of July 2006, the city of Atlanta had a population of 486,411 and a metropolitan population of 5,138,223, making it the nation's ninth-largest metro area. Residents of the city are known as Atlantans. The U.S. Geological Survey National Mapping Information locates city of Atlanta at 33° 45' 23" N 084° 23' 36" W.

Atlanta has in recent years undergone a transition from a city of regional commerce to a city of international influence. Between 2000 and 2006, the Atlanta metropolitan area grew 20.5%, making it the fastest growing metropolitan area in the nation. Atlanta is often considered a poster child for cities worldwide experiencing rapid growth and urban sprawl.

During the Civil Rights Movement, Atlanta stood apart from southern cities that supported segregation, touting itself as "The City Too Busy to Hate." The city's progressive civil rights record and existing population of blacks made it increasingly popular as a relocation destination for black Americans. Blacks soon became the dominant social and political force in the city, though today some measure of demographic diversification has taken place. Along with St. Louis and Los Angeles, Atlanta is one of three cities in the United States to have hosted the Summer Olympic Games.

On December 21, 1836 the Georgia General Assembly voted to build the Western and Atlantic Railroad to provide a trade route to the Midwest. The area around the eastern terminus to the line began to develop. By 1842, the settlement had six buildings and 30 residents and the town was renamed "Marthasville." After a few renames, the Chief Engineer of the Georgia Railroad, J. Edgar Thomson, suggested that the area be renamed "Atlantica-Pacifica", which was quickly shortened to "Atlanta." The residents approved, and the town was incorporated as "Atlanta" on December 29, 1847.

As more railroads were constructed, the town experienced a small boom, reaching 2,500 in population. In 1848, the first mayor was elected, the first homicide occurred and the first jail was built. Sidewalks were constructed and a town marshal appointed. By 1854 another railroad connected Atlanta to LaGrange, and the town grew to 7,741 by 1860.

During the American Civil War, Atlanta served as an important railroad and military supply hub. In 1864, the city became the target of a major Union invasion. The area now covered by Atlanta was the scene of several battles, including the Battle of Peachtree Creek, the Battle of Atlanta, and the Battle of Ezra Church. On September 1, 1864, Confederate General John Bell Hood evacuated Atlanta after a four-month siege mounted by Union General William T. Sherman and ordered all public buildings and possible Confederate assets destroyed. The next day, Mayor James Calhoun surrendered the city, and on September 7 Sherman ordered the civilian population to evacuate. He then ordered Atlanta burned to the ground on November 11 in preparation for his punitive march south, though spared the city's churches and hospitals.

The rebuilding of the city—immortalized in the city's symbol, the phoenix—was gradual. From 1867 until 1888, U.S. Army soldiers occupied McPherson Barracks in southwest Atlanta to ensure Reconstruction era reforms. To help the newly freed slaves, the Federal Government set up a Freedmen's Bureau, which helped establish what is now Clark Atlanta University, one of several historically black colleges in Atlanta.

In 1868, Atlanta became the fifth city to serve as the state capital. Henry W. Grady, the editor of the Atlanta Constitution, promoted the city to investors as a city of the "New South," one built on a modern economy, less reliant on agriculture. In the 1880s Georgia School of Technology and Atlanta Hospital were founded.

As Atlanta grew, ethnic and racial tensions mounted. The Atlanta Race Riot of 1906 left at least 27 dead and over seventy injured. In 1913, Leo Frank, a Jewish supervisor at a factory in Atlanta was put on trial for raping and murdering a thirteen-year old white employee from a suburb of Atlanta, ultimately resulting in Frank's lynching.

With the entry of the United States into World War II, soldiers from around the Southeastern United States went through Atlanta to train and later be discharged at Fort McPherson. War-related manufacturing such as the Bell Aircraft factory in the suburb of Marietta helped boost the city's population and economy. Shortly after the war, the Communicable Disease Center (CDC) was founded in Atlanta.

In the wake of the landmark U.S. Supreme Court decision Brown v. Board of Education, which helped usher in the Civil Rights Movement, racial tensions in Atlanta began to express themselves in acts of violence. On October 12, 1958, a Reform Jewish temple on Peachtree Street was bombed. The "Confederate Underground" claimed responsibility. Many believed that Jews, especially those from the northeast, were advocates of the Civil Rights Movement.

In the 1960s, Atlanta was a major organizing center of the US Civil Rights Movement, with Dr. Martin Luther King and students from Atlanta's historically black colleges and universities playing major roles in the movement's leadership. On October 19, 1960, a sit-in at the lunch counters of several Atlanta department stores led to the arrest of Dr. King and several students, drawing attention from the national media and from presidential candidate John F. Kennedy. Despite this incident, Atlanta's political and business leaders fostered Atlanta's image as "the city too busy to hate." In 1961, Mayor Ivan Allen Jr. became one of the few Southern white mayors to support desegregation of Atlanta's public schools. While the city mostly avoided confrontation, minor race riots did occur in 1965 and in 1968.

In 1990, Atlanta was selected as the site for the Centennial Olympic Games 1996 Summer Olympics. Following the announcement, Atlanta undertook several major construction projects to improve the city's parks, sports facilities, and transportation. Former Mayor Bill Campbell allowed many "tent cities" to be built. Atlanta became the third American city to host the Summer Olympics, after St. Louis and Los Angeles. The games themselves were marred by numerous organizational inefficiencies as well as the Centennial Olympic Park bombing.