1. On June 3, 1741, Swedish Lutheran theologian and botanist supported by Queen Ulrika Eleonora of Sweden, Peter Kalm, arrived in the American colonies to study their plants and animals. He landed in Pennsylvania, traveled through Delaware, and eventually made his way to Canada. Kalm's observations and writings would later become an important source of information for early American natural history.

2. Delaware officially became the first state to ratify the United States Constitution on June 3, 1788, making Delaware the first state of the new nation. Their declaration of independence announces: "The said representatives, on behalf of ourselves and our constituents, do by these presents, as they unitedly have already done, accept and ratify the said Constitution."

3. The Battle of Gettysburg, considered one of the most significant battles of the American Civil War, began on June 3, 1863. The Delaware 1st Regiment fought on the Union side under the command of Colonel Henry S. McComb throughout the three-day battle, with one company losing 34 men on July 2nd alone.

4. On June 3, 1918, Delaware voters approved the 18th Amendment to the U.S. Constitution, which banned the manufacture, sale, and transportation of alcohol in the United States. Delaware was one of the first states to ratify the amendment, which eventually led to Prohibition, a national era of lawlessness and bootlegging.

5. On June 3, 1957, Delaware Governor J. Caleb Boggs signed a bill that officially created a separate state division for Motor Vehicles. The Delaware Division of Motor Vehicles (DMV) would go on to become a highly respected division of the state's government, responsible for driver's licenses, registration plates, and other vehicle-related services for the state's residents.