1. In 1846, the United States Congress passed an act which officially established the Washington Territory. Prior to this, the region had been part of the Oregon Territory, which encompassed a vast area of the Pacific Northwest.

2. On August 3, 1909, the Seattle Times reported the arrival of the first car to traverse the rugged Cascade Mountains via the newly-opened Stevens Pass Highway. This marked a significant milestone in the development of Washington's transportation infrastructure.

3. August 3, 1921 saw the dedication of the new Seattle Public Library building in downtown Seattle. The Beaux-Arts style building featured a grand central staircase and atrium, as well as reading rooms, art galleries, and other amenities.

4. In 1963, August 3 was declared "Little League Day" in the city of Everett, Washington. The occasion was marked by a parade and a series of baseball games featuring local Little League teams.

5. August 3, 1984 saw the opening of one of Washington's most iconic landmarks: the Space Needle. Built for the 1962 Seattle World's Fair, the Needle offers stunning panoramic views of the surrounding city and mountains.