1. Delaware was the first state to ratify the U.S. Constitution on December 7, 1787. While this did not happen on December 3 specifically, it is a significant historical event for the state.

2. On December 3, 1904, the first New Castle County Automobile Club was formed in Wilmington. This club was one of the first automobile clubs in the country and marked the beginning of the automobile industry in Delaware.

3. In 1863, during the Civil War, the Battle of Laurel Hill took place in Virginia. Many Union soldiers fighting in this battle were from Delaware, including the 1st Delaware Volunteer Infantry. This battle occurred on December 3.

4. On December 3, 1930, Delaware Park Racetrack opened, becoming the first horse racing track in the state. The racetrack is still open today and is a popular destination for horse racing enthusiasts.

5. December 3, 1954, was the day that Delaware native John McKinly became the first Governor of Delaware. He was elected to the position under the new Delaware Constitution, which created a separate executive branch for the state. McKinly served as governor until 1960.