California is the country's most populous state and a Democratic stronghold.
Trump will arrive in San Diego at 11:30 am (1930 GMT) and then go to nearby Otay Mesa to view eight prototypes for the wall he wants to build on the border with Mexico.
Ariel Norcross, demonstrating Monday outside the Federal Building, carried a placard that read "No hate in the Golden State."
"I don't want him, his hateful rhetoric, his hateful administration, any of his policies in my state, in my country," said Norcross.
"It's already been a waste of money to build eight prototypes that are not doing anything," he added.
"People will find their way here," he said as he walked in a procession featuring placards denouncing the wall plan and children in Mexican ponchos riding on their parents' shoulders.
"I don't know why he took so long to get here but I think he is realizing that this is the strongest point of resistance, here at the border and in the state of California," protester Ali Torabei said.
After viewing the wall prototypes, Trump is scheduled to give a speech at a military base in Miramar and then head to Los Angeles for a Republican fund-raising dinner.
The speaker of California's senate, Democrat Kevin de Leon, led an anti-Trump rally Monday in Beverly Hills, where the dinner will be held.
The largest rally scheduled for Tuesday will be at a church in San Ysidro, from which you can see the border. Hundreds of people are expected to take part.
Demonstrators plan to erect a large sign calling on Trump to "build bridges, not walls."
But a pro-Trump rally in favor of the wall project is also scheduled.
Trump is coming at a time of tense relations between California and the federal government, which has sued the state over its policy of not cooperating with US immigration authorities seeking to detain undocumented immigrants.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)
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