1. May 1, 1873: Yellow Springs College opened its doors on this day. It was founded by the Unitarian minister Antiochian Charles B. Hill and aimed to provide quality education to economically disadvantaged students. The college has since become known for its liberal arts curriculum and progressive social justice initiatives.

2. May 1, 1890: Ohio became the first state to recognize Labor Day as an official holiday. This followed years of labor unrest and calls for improved working conditions, particularly for factory workers who often toiled for long hours in dangerous conditions. Today, Labor Day is celebrated across the country as a tribute to the contributions of workers to the economy and society.

3. May 1, 1915: The first coast-to-coast telephone call in the United States was made on this day between New York and San Francisco. The call was placed by Alexander Graham Bell, the inventor of the telephone, and marked a major landmark in the development of telecommunications technology.

4. May 1, 1939: The world-famous Ohio River Flood peaked on this day, causing widespread destruction and loss of life to communities along the river. The flood was caused by heavy rains and snowmelt, and was exacerbated by poor infrastructure and inadequate disaster preparation measures. Today, the flood remains one of the worst natural disasters in Ohio's history.

5. May 1, 1978: The Ohio state legislature passed SB 107, a landmark piece of legislation that established clear procedures for the investigation and prosecution of police misconduct. The bill was seen as a major step forward in efforts to promote accountability and transparency in law enforcement, and has since served as a model for similar reforms in other states across the country.