On September 3, the following notable historical events related to Missouri have been recorded:

• 1804: The Lewis and Clark Expedition was near present-day Yankton, South Dakota, across from Missouri’s Atchison County, on or around September 3. They continued documenting the region’s geography and interactions with the Yankton Sioux, advancing their exploration of the Louisiana Purchase.
• 1838: During the Mormon War in Missouri, tensions escalated. On or around September 3, non-Mormon vigilantes in Daviess and Carroll Counties intensified their campaign against Mormon settlers, with skirmishes contributing to the conflict that led to the Mormon expulsion order later in 1838.
• 1861: During the Civil War, Missouri remained a battleground. On September 3, Confederate forces under Sterling Price were advancing toward Lexington, Missouri, while Union forces were preparing defenses, setting the stage for the First Battle of Lexington later that month.
• 1876: The St. Louis-based Anheuser-Busch brewery began expanding its refrigerated railcar system around September 3, enabling broader distribution of Budweiser and reinforcing Missouri’s leadership in the national brewing industry.
• 1904: The St. Louis World’s Fair, or Louisiana Purchase Exposition, was ongoing, with September 3 featuring international scientific exhibits and cultural performances, highlighting Missouri’s global prominence.
• 1964: The St. Louis Cardinals played a notable game against the New York Mets at Busch Stadium on September 3, with Lou Brock stealing two bases and contributing to a Cardinals victory, reinforcing Missouri’s baseball legacy during their World Series-winning season.