May is Asian American and Pacific Islander Heritage Month. The month was chosen because two important milestones in Asian/Pacific American history occurred in May: the arrival in the United States of the first Japanese immigrants (May 7, 1843) and contributions of Chinese workers to the building of the transcontinental railroad, completed May 10, 1869. In 1992, Congress expanded the observance to a monthlong celebration that is now known as Asian American and Pacific Islander Heritage Month.
Thanks to the United States Census Bureau for providing the following fun facts.