In 1971, Berkeley, Calif., became the first place in the nation to deem itself a sanctuary city, at the time to provide refuge for sailors who protested the Vietnam War.

Today, at least 25 cities and counties in California have declared themselves sanctuaries for undocumented immigrants by passing laws that limit how much they will cooperate with federal efforts to deport people.

Those policies could soon make California a greater target for the Trump administration as federal officials try to punish governments with sanctuary policies.

President Trump is expected to sign an executive order on Monday night directing federal officials to publish a list of all jurisdictions that have declared themselves sanctuaries for undocumented immigrants in the United States. It is unclear how Mr. Trump intends to use the list, but it is possible that he may try to cut funding or take legal action against the governments that are identified.

California has long been home to more undocumented immigrants than any other state and currently has about 1.8 million undocumented residents, according to the Pew Research Center. Amid threats of mass deportations during Mr. Trump’s first term, California declared itself a sanctuary state in 2017.

Here is how local policies in California are playing out during the second Trump administration:

What does it mean to be a sanctuary?

Oakland, Sacramento and San Diego are among the California cities that have declared themselves “sanctuaries” for undocumented immigrants.