1. First day of Summer: June 21 marks the official start of summer in Delaware and the Northern Hemisphere. The summer solstice is the longest day of the year, with the sun appearing highest in the sky and the day lasting for approximately 14 hours.

2. The Battle of Gettysburg: On June 21, 1863, one of the bloodiest battles of the American Civil War began in nearby Gettysburg, Pennsylvania. Thousands of Union and Confederate soldiers were killed or wounded in the three-day battle, and it is considered a turning point in the war.

3. Delaware ratifies the Constitution: On June 21, 1788, Delaware became the first state to ratify the United States Constitution, making it the first state in the Union. This event is celebrated annually as Delaware Day.

4. Women's suffrage: On June 21, 1913, feminist and suffragist Alice Paul organized a suffrage parade in Washington D.C., calling for the right for women to vote. The parade became infamous when women were attacked by an angry mob, but it also brought national attention to the suffrage movement and helped lead to the passing of the 19th Amendment.

5. Wilt Chamberlain traded: On June 21, 1968, the Philadelphia 76ers traded basketball star Wilt Chamberlain to the Los Angeles Lakers. Chamberlain was a dominant force in the NBA and helped lead the Lakers to an NBA Championship in 1972.