Santa Ana has always been the principal administrative and political center of Orange County. After several unsuccessful attempts to separate from Los Angeles County, Orange County was finally formed in 1889, and Santa Ana was chosen as the county seat. William H. Spurgeon was elected chairman of the County Board of Supervisors.

The "Old Orange County Courthouse" as it is now called is a tangible reminder of William H. Spurgeon. In 1893, several offers of land for a county courthouse were made. It was his offer that was accepted for the site. The city paid $8,000 for the block east of West St. and north of Sixth St., promising to erect the courthouse within ten years. It was completed, dedicated, and opened for business in September, 1901. Since then many movies have been filmed there. Many politicians, including President Richard M. Nixon, have held rallies or given speeches there. A plaque beside the south steps reads: "Significant and far-reaching court decisions were handed down here, including the 'Whipstock' case which dealt with slant oil drilling, interpretation of farm labor law, and the Overell trial resulting in law regulating explosives." The latter involved a young couple accused of murdering her parents on March 15, 1947, on their boat in Newport Harbor.