1. The District of Columbia was named after Christopher Columbus.
On July 1, 1790, President George Washington signed the "Residence Act," which established a 100-square-mile federal district along the Potomac River. It was named the District of Columbia in honor of Christopher Columbus, who had been born in Genoa, Italy.

2. The District of Columbia was not always the capital of the United States.
Until 1800, Philadelphia was the capital of the United States. However, after a decade of construction, the new capital in the District of Columbia became ready for occupancy by the federal government on July 1, 1800.

3. The District of Columbia was an important center for the abolitionist movement.
In the 19th century, the District of Columbia was an important center for the abolitionist movement. Many free African Americans lived in the city, and the local government was forced to confront the issue of slavery. In 1862, President Abraham Lincoln signed the Emancipation Proclamation, which freed slaves in the District of Columbia.

4. On July 1, 1892, the first electric streetcars began operating in Washington, D.C.
Before the advent of electric streetcars, horse-drawn streetcars were the primary mode of public transportation in Washington, D.C. On July 1, 1892, the first electric streetcars began operating in the city. This made transportation faster, more efficient, and safer for passengers and animals.

5. On July 1, 1971, the Twenty-Sixth Amendment to the United States Constitution was ratified.
The Twenty-Sixth Amendment to the United States Constitution lowered the voting age from 21 to 18. It was ratified by the requisite 38 states on July 1, 1971. This amendment was fueled by opposition to the Vietnam War, with many arguing that if 18-year-old men could be drafted to fight in the war, they should also have the right to vote.