When appointed to fill the seat left vacant by the death of Supervisor Oran L. Slaght in 1960, Ralph Mehrkens had little political experience. His only public office was serving as the head of the Santa Clara County Taxpayers Association in 1959. In his fifteen years as District 4 county supervisor, however, Supervisor Mehrkens was respected as a fair and decent politician, avoiding November runoff elections three times by being confirmed early in the June primaries. Mehrkens served during a period of tremendous growth and change in the Santa Clara Valley. While cities were hastily competing to annex territory, Mehrkens worked to foster intergovernmental cooperation to benefit everyone. He was called the "father" of mutual aid pacts between the cities and county, allowing for more efficient fire and police protection. He dreamed of a day when city and county government would act as one (like San Francisco), reducing the cost of government operation. Mehrkens was described by his administrative assistant as the type who "did things quietly and never went home with unanswered phone calls." The easy-going Mehrkens was defeated by Rod Diridon in 1974, and lost a bid to reclaim his seat in 1978.
The Mehrkens family left San Francisco in 1911 to settle in San Jose. Ralph Mehrkens attended local schools, graduating from San Jose High School in 1927. After graduation, Mehrkens was hired by J.Q. Patton to work at the Security Warehouse and Cold Storage Company. Eventually, he became assistant general manager, serving the company for thirty-three years. During World War II, he had charge of all fresh and frozen provisions for the troops in the Pacific front. Realizing the lack of cold storage facilities on the battle lines, Mehrkens proposed that meat be precut into small packages. This innovative idea prevented wasting millions of pounds of food, and money.

After forty-five years of marriage, his wife Edna died of cancer in 1974. He later married his longtime administrative assistant, Verlie, enjoying happy years until his death on August 18, 1991.