How old is UPSA?

Could you please clarify the age of UPSA for me? I understand that UPSA is a well-established organization, but I'm curious about its exact founding date and how many years it has been operating. Is there a specific milestone or event that marks the beginning of UPSA's history? Additionally, I'd be interested to know if UPSA has undergone any significant changes or expansions over the years that have contributed to its longevity and success.