Dallas formally became a city on February 2, 1856, shortly after the Republic of Texas was annexed by the United States in 1845 and Dallas County was established. In the mid-1800s, French Socialists founded La Réunion along the Trinity River in what is now West Dallas, though the community was short-lived.

The construction of railroads transformed Dallas into a thriving business and trading center by the late 19th century, attracting workers from across Texas, the South, and the Midwest. The Praetorian Building, completed in 1909, was among the first skyscrapers west of the Mississippi and symbolized Dallas’s growing prominence. Leisure and entertainment also expanded, with racetracks and jockey clubs establishing the city’s early recreational culture.

However, Dallas’s rapid growth also reflected the racial tensions of the era. In 1910, a white mob lynched Allen Brooks, a Black man accused of a crime, in a brutal public display downtown—a dark chapter in the city’s history that serves as a reminder of the challenges faced by African Americans in early 20th-century Dallas.

The 1920s brought cultural and international connections, including visits by Mexican President Álvaro Obregón to Little Mexico, a neighborhood shaped by Latin American migration. Despite the Great Depression, Dallas flourished economically, particularly after the East Texas oil boom in 1930, which established the city as a financial hub for the oil industry in Texas and Oklahoma.

During World War II, Dallas became a major manufacturing center for military vehicles and aircraft. The Ford plant in East Dallas produced over 94,000 jeeps and 6,000 trucks, while North American Aviation built more than 18,000 aircraft, including P-51 Mustang fighters and B-24 Liberator bombers. These contributions cemented Dallas’s role as a critical center for industry, commerce, and transportation in the United States.