The rodeo is all I have found so far.
An online pay to view newspaper archive site does not have the Prescott newspaper. A second newspaper archival site stops at the year 1908 and does not go beyond 1908. I am still digging for other events. That far back is probably going to mean looking at newspaper on microfilm at an academic library or a very large public library in AZ that carries the Yavapai county papers. Anyone live in AZ?
There is a college campus, there is part of an Indian reservation, there are parts of 4 national parks and numerous "wilderness areas"; the Hospital for Disabled Miners, and according to Wikipedia, currently
" Prescott hosts annual events such as Frontier Days, The World's Oldest Rodeo (1888) (featured in the 1972 film Junior Bonner), Easter Egg-Stravaganza, the Bluegrass Festival, Earth Day, July 4 Celebration, Tsunami on the Square, art festivals, a Cinco de Mayo celebration, Navajo Rug Auction, Pumpkin Patch Carnival, World’s Largest Gingerbread Village (actually on the Yavapai-Prescott Indian Tribe reservation), Prescott Film Festival, Folk Arts Fair, parades, the Acker Music Festival, The Cowboy Poets Gathering, the Prescott Highland Games, Courthouse Lighting, Whiskey Off Road and Ragnar Relay Del Sol. "
http://en.wikipedia.org/wiki/Prescott,_Arizona
Of the above events, we can eliminate the Easter Egg event, (due to timing) ;Earth Day,Whiskey Off-Road , and Tsunami on the Square as being there in 1960. Still researching the other events to see when they were first held.
The Disabled Miners hospital has been there since 1929.
Prescott is 90 miles from Phoenix. I wonder how far back Phoenix Police Department MP files go.