1. May 1, 1850: California became a state
California officially became the 31st state of the United States on May 1, 1850. Four months earlier, in December 1849, California had held a constitutional convention and adopted a state constitution that abolished slavery.

2. May 1, 1886: Start of the eight-hour workday movement
On May 1, 1886, labor unions across the United States went on strike to demand an eight-hour workday. This movement eventually led to the establishment of the eight-hour workday as a standard practice in many industries.

3. May 1, 1903: Motion picture industry begins in California
The first motion picture studio in the United States was established in May 1903 in California by a group of New York filmmakers. The state's mild climate and varied scenery made it an ideal location for the film industry, which soon became a major economic force in California.

4. May 1, 1917: Construction begins on the Hoover Dam
Construction on the Hoover Dam, one of the largest and most ambitious engineering projects in U.S. history, began on May 1, 1917. The dam was built across the Colorado River on the border between Nevada and Arizona, and provided power and water to cities in both states.

5. May 1, 1971: Protests against the Vietnam War
On May 1, 1971, thousands of protesters gathered in Los Angeles to protest against the Vietnam War. The protest turned violent when police clashed with demonstrators, resulting in dozens of injuries and arrests. The event helped to galvanize opposition to the war across the country.