Although most lived in rural areas, more than 1,000 resided in both Galveston and Houston by 1860, with several hundred in other large towns. More isolated geographically, planters and other slaveholders had migrated into Texas from eastern states to escape the fighting, and many brought enslaved people with them, increasing by the thousands the enslaved population in the state at the end of the Civil War.

The Texas Historical Commission and Galveston Historical Foundation report that Granger’s men marched throughout Galveston reading General Order No. 3 first at Union Army Headquarters at the Osterman Building (formerly at the intersection of Strand Street and 22nd Street, since demolished), in the Strand Historic District. Next they marched to the 1861 Customs House and Courthouse before finally marching to the Negro Church on Broadway, since renamed Reedy Chapel-AME Church. The order informed all Texans that, in accordance with a Proclamation from the Executive of the United States, all slaves were free: The people of Texas are informed that, in accordance with a proclamation from the Executive of the United States, all slaves are free. This involves an absolute equality of personal rights and rights of property between former masters and slaves, and the connection heretofore existing between them becomes that between employer and hired labor. The freedmen are advised to remain quietly at their present homes and work for wages. They are informed that they will not be allowed to collect at military posts and that they will not be supported in idleness either there or elsewhere.

During the American Civil War, President Abraham Lincoln issued the preliminary Emancipation Proclamation on September 22, 1862.

Emancipation Proclamation was formally issued on January 1, 1863, declaring that all enslaved persons in the Confederate States of America in rebellion and not in Union hands were freed.

By 1865, there were an estimated 250,000 enslaved people in Texas.

Despite the surrender of General Robert E. Lee at the Old Appomattox Court House on April 9, 1865, the western Army of the Trans-Mississippi did not surrender until June 2.

Although this event is popularly thought of as "the end of slavery", the Emancipation Proclamation did not apply to those enslaved in Union-held territory, who would not be freed until a proclamation several months later, on December 18, 1865, stating that the Thirteenth Amendment had been ratified on December 6, 1865.

Formerly enslaved people in Galveston celebrated after the announcement. Freedmen in Texas organized the first of what became the annual celebration of "Jubilee Day" on June 19. Early celebrations were used as political rallies to give voting instructions to newly freed slaves. Early independence celebrations often occurred on January 1 or 4.

In some cities black people were barred from using public parks because of state-sponsored segregation of facilities. Across parts of Texas, freed people pooled their funds to purchase land to hold their celebrations. The day was first celebrated in Austin in 1867 under the auspices of the Freedmen's Bureau, and it had been listed on a "calendar of public events" by 1872. That year black leaders in Texas raised $1,000 for the purchase of 10 acres (4 ha) of land to celebrate Juneteenth, today known as Houston's Emancipation Park.

The freedom of formerly enslaved people in Texas was given final legal status in a series of Texas Supreme Court decisions between 1868 and 1874.

The observation was soon drawing thousands of attendees across Texas; an estimated 30,000 black people celebrated at Booker T. Washington Park in Limestone County, Texas, established in 1898 for Juneteenth celebrations.

In the early 20th century, economic and political forces led to a decline in Juneteenth celebrations. From 1890 to 1908, Texas and all former Confederate states passed new constitutions or amendments that effectively disenfranchised black people, excluding them from the political process. White-dominated state legislatures passed Jim Crow laws imposing second-class status.

The Great Depression forced many black people off farms and into the cities to find work. In these urban environments, African Americans had difficulty taking the day off to celebrate.

From 1936 to 1951, the Texas State Fair served as a destination for celebrating the holiday, contributing to its revival. In 1936 an estimated 150,000 to 200,000 people joined the holiday's celebration in Dallas.

In 1938, Texas governor J. V. Allred issued a proclamation stating in part: Whereas, the Negroes in the State of Texas observe June 19 as the official day for the celebration of Emancipation from slavery; and Whereas, June 19, 1865, was the date when General Robert [sic] S. Granger, who had command of the Military District of Texas, issued a proclamation notifying the Negroes of Texas that they were free; and Whereas, since that time, Texas Negroes have observed this day with suitable holiday ceremony, except during such years when the day comes on a Sunday; when the Governor of the State is asked to proclaim the following day as the holiday for State observance by Negroes; and Whereas, June 19, 1938, this year falls on Sunday; NOW, THEREFORE, I, JAMES V. ALLRED, Governor of the State of Texas, do set aside and proclaim the day of June 20, 1938, as the date for observance of EMANCIPATION DAY in Texas, and do urge all members of the Negro race in Texas to observe the day in a manner appropriate to its importance to them.

From 1940 through 1970, in the second wave of the Great Migration, more than five million black people left Texas, Louisiana and other parts of the South for the North and the West Coast. As historian Isabel Wilkerson writes, "The people from Texas took Juneteenth Day to Los Angeles, Oakland, Seattle, and other places they went".

In 1945, Juneteenth was introduced in San Francisco by an immigrant from Texas, Wesley Johnson.

Seventy thousand people attended a "Juneteenth Jamboree" in 1951.

During the 1950s and 1960s, the Civil Rights Movement focused the attention of African Americans on expanding freedom and integrating. As a result, observations of the holiday declined again (though it was still celebrated regionally in Texas).

It soon saw a revival as black people began tying their struggle to that of ending slavery. In Atlanta, some campaigners for equality wore Juneteenth buttons. During the 1968 Poor People's Campaign to Washington, DC, called by Rev. Ralph Abernathy, the Southern Christian Leadership Conference made June 19 the "Solidarity Day of the Poor People’s Campaign".

In 1974, Houston began holding large-scale celebrations again.

Around 30,000 people attended festivities at Sycamore Park in Fort Worth the following year.

The 1978 Milwaukee celebration was described as drawing over 100,000 attendees.

In 1979, Democratic State Representative Al Edwards of Houston, Texas successfully sponsored legislation to make Juneteenth a paid Texas state holiday. The same year he hosted the inaugural Al Edwards’ Prayer Breakfast and Commemorative Celebration on the grounds of the 1859 home, Ashton Villa. As one of the few existing buildings from the Civil War era and popular in local myth and legend as the location of Major General Granger’s announcement, Edwards’ annual celebration includes a local historian dressed as the Union general reading General Order No. 3 from the second story balcony of the home. The Emancipation Proclamation is also read and speeches are made.

The bill passed through the Texas Legislature in 1979 and was officially made a state holiday on January 1, 1980.

By the 1890s Jubilee Day had become known as Juneteenth.

Most states recognize it in some way, either as a ceremonial observance or a state holiday. Texas was the first state to recognize the date, in 1980.

In 1996, the first legislation to recognize "Juneteenth Independence Day" was introduced in the U.S. House of Representatives, H.J. Res. 195, sponsored by Barbara-Rose Collins (D-MI).

In 1997, Congress recognized the day through Senate Joint Resolution 11 and House Joint Resolution 56.

In 1999, Ralph Ellison's novel Juneteenth was published, increasing recognition of the holiday. By 2006, at least 200 cities celebrated the day.

In 2013, the U.S. Senate passed Senate Resolution 175, acknowledging Lula Briggs Galloway (late president of the National Association of Juneteenth Lineage) who "successfully worked to bring national recognition to Juneteenth Independence Day", and the continued leadership of the National Juneteenth Observance Foundation.

Longstanding urban legend places the historic reading of General Order No. 3 at Ashton Villa, however no extant historical evidence supports such claims. On 29 June 2014, the Galveston Historical Foundation and Texas Historical Commission erected a Juneteenth plaque where the Osterman Building once stood signifying the location of Major General Granger's Union Headquarters and subsequent issuance of his general orders.

In 2018, Apple added Juneteenth to its calendars in iOS under official US holidays.

Recognition of Juneteenth varies across the United States. It is not officially recognized by the federal government, although the Senate unanimously passed a simple resolution in 2018 in honor of the day, and legislation has been introduced in Congress several times to make it either a "national day of observance" (akin to Flag Day or Patriot Day) or a full-scale federal holiday.

By 2019, 47 states and the District of Columbia recognized Juneteenth, although only one state (Texas) has adopted the holiday as a paid holiday for state employees.

In 2020, several American corporations and educational institutions including Twitter, the National Football League, Nike, announced that they would treat Juneteenth as a company holiday, providing a paid day off to their workers, and Google Calendar added Juneteenth to its US Holidays calendar.

Representative Al Edwards died of natural causes April 29, 2020 at the age of 83, but the annual prayer breakfast and commemorative celebration continued at Ashton Villa with the late legislator's son, Jason Edwards, speaking in his father’s place.

In 2020, in the midst of the COVID-19 pandemic and the worldwide protests sparked by the police killing of George Floyd, controversy ensued when President Donald Trump scheduled his first political rally since the pandemic's outbreak for Juneteenth in Tulsa, Oklahoma, site of the 1921 race massacre in the Greenwood district.

In 2020, Massachusetts Governor Charles Baker issued a proclamation that the day would be marked as "Juneteenth Independence Day". This followed the filing of bills by both the House and Senate to make Juneteenth a state holiday. Baker did not comment on these bills specifically, but promised to grant the observance of Juneteenth greater importance.

North Dakota Governor Doug Burgum announced that the state would formally recognize Friday, June 19, 2020, as Juneteenth Day in North Dakota for the year 2020.

Governor Kristi Noem of South Dakota proclaimed June 19, 2020, as Juneteenth Day, spurring calls for it to be recognized annually, rather than just for 2020.

In 2020, Juneteenth was formally recognized by New York City (as an annual official city holiday and public school holiday, starting in 2021).