San Mateo County is among 35 jurisdictions in 19 states that have personnel from the U.S. Department of Justice monitoring the polls on Election Day.
The other county in California along with San Mateo that will be monitored Tuesday is Sacramento County.
Attorney General Jeff Sessions issued a statement saying, "This year we are using every lawful tool that we have, both civil and criminal, to protect the rights of millions of Americans to cast their vote unimpeded at one of the more than 170,000 precincts across America."
At the polling stations that are being monitored, the Department of Justice's Civil Rights Division plans to gather information on, among other things, whether voters are subject to different voting qualifications based on race, color or membership in a language minority group.
Jim Irizarry, San Mateo County's assistant chief elections officer and assessor-county clerk recorder, said that based on the interaction elections officials had with justice officials, the monitoring is a "normal routine function," though he noted that the county is operating under a new election model this election.
The county is one of five in California that is conducting elections under the California Voter's Choice Act, in which ballots are all mailed out to voters and people can mail them back or drop them off at locations around the county.
The other participating counties are Sacramento, Napa, Madera and Nevada.
Irizarry said in this election the county has reached a historic milestone. For the first time, more than 400,000 eligible voters have registered. The county currently has about 503,000 eligible voters and about 401,000 have registered, Irizarry said.