Elections in San Diego County could be conducted entirely by mail under legislation introduced Monday by state Sen. Christine Kehoe, D-San Diego.

All-mail balloting would save local governments millions of dollars and increase voter participation, according to the senator.

The legislation, SB 304, would create a five-year pilot program. At the conclusion of the program, the county would be required to issue a report to the Legislature and the Secretary of State’s Office on costs and voter turnout.

The law, if approved, would apply to local, state and federal races on San Diego County ballots. Individual jurisdictions, such as cities, would have the option of using the system.

San Diego would become the only county in the state to have all-mail voting. Three small counties have had similar pilot programs, but they are not in place now.

In California’s general election last year, 55 percent of San Diego County voters cast ballots by mail in contrast to the statewide figure of 48 percent.