His father, John, had participated in the Gold Rush in California and dug up 80 nuggets to purchase the undeveloped property, which became the Shields Ranch.
He was the third child, and named Peter after his mother's first husband, who died of cholera on the ship taking them from the Isthmus of Panama to San Francisco, where she buried him in the sandy cliffs of the new city.
At 17 he graduated from Christian Brothers College in Sacramento, then studied law reading in the office of the distinguished Jurist Amos Catlin.
He raised a prize-winning herd of Jersey Cattle and won so many prizes at the California State Fair, he finally withdrew to give others a chance to win.
In keeping with this pledge, he wrote an annual birth message in the Sacramento Bee imparting his generous and intelligent philosophy and personal wisdom, applied to the problems of the time and looking into the future.