1. In 1798, construction began on the first executive mansion in Washington, D.C. This building, known as the President's House, would later be renamed the White House and become the official residence of the president of the United States.

2. On May 3, 1802, the Washington Canal opened, connecting the Potomac River to the Anacostia River and providing a way to transport goods between Georgetown and the Navy Yard. However, the canal was plagued by problems such as leaks and blockages and fell into disuse by the mid-19th century.

3. In 1863, Confederate General Thomas "Stonewall" Jackson was shot by friendly fire during the Battle of Chancellorsville in Virginia. He was taken to a field hospital in Guinea Station, Virginia, where his left arm was amputated. He died of pneumonia eight days later and was buried in Lexington, Virginia.

4. On May 3, 1921, the Washington Senators played their first game at Griffith Stadium, which was located at 7th Street and Florida Avenue NW. The Senators defeated the New York Yankees 6-5 in front of a crowd of over 20,000 fans.

5. In 1971, the Washington Metropolitan Area Transit Authority (WMATA) began service on the first line of the Washington Metro, a rapid transit system that serves Washington, D.C. and its suburbs. The initial line, known as the Red Line, ran from Farragut North to Rhode Island Avenue-Brentwood. Today, the Metro consists of six lines and serves over 600,000 passengers per weekday.