An archaeologist and director of the Rochester Museum, Parker was a primary advocate for a national day of honor. In 1912, he persuaded the Boy Scouts of America to adopt a "First Americans" day.

As president of the Society of American Indians, Coolidge issued a formal proclamation in 1915 declaring the second Sunday of May as American Indian Day.

The journey of American Indian Day—the precursor to today’s National Native American Heritage Month —is a century-long story of advocacy, from solo horseback rides to federal proclamations. Initially conceived as a single day of recognition, it has evolved into a nationwide celebration of Indigenous cultures and resilience. The Pioneers of Recognition

The drive for a formal holiday began in the early 20th century, led by Indigenous activists who sought both cultural recognition and legal citizenship for Native Americans.