1. On August 4, 1964, the Arkansas Rivers and Harbors Act was signed into law by President Lyndon B. Johnson. The act authorized the improvement and maintenance of the Arkansas River and its tributaries for navigation, flood control, and other beneficial purposes.

2. In 1865, on August 4, Union forces under the command of General Powell Clayton clashed with Confederate forces near Wallace's Ferry in Monroe County. The battle resulted in a Union victory and marked the end of organized Confederate resistance in the area.

3. On August 4, 1927, the legendary blues guitarist and singer Robert Johnson was born in Hazlehurst, Mississippi. Though he never lived in Arkansas, his recordings and style of guitar playing would go on to influence countless musicians from the state and beyond.

4. The 875th Engineer Battalion of the Arkansas Army National Guard was activated on August 4, 1943, and would go on to serve in World War II. The battalion was responsible for constructing roads, bridges, and other infrastructure in support of Allied operations.

5. On August 4, 1986, a tornado struck the town of Hampton in southern Arkansas, causing extensive damage and injuring 11 people. The tornado was part of a larger outbreak that affected several states and claimed 15 lives in total.