Lorena Gonzalez Fletcher, chief officer of the California Labor Federation, which urged Mr. Newsom to sign the bill, said it was a victory for farmworkers all across the state.
“In this historic time when workers want a union more than ever before, everything we do — including legislatively — must be focused on organizing,” she said. “It’s natural that in California, our farmworkers will be leading the way.”
In August, dozens of farmworkers marched more than 330 miles through the Central Valley to Sacramento to push for Mr. Newsom to sign the bill. The march was symbolic and mirrored a 1966 trek spearheaded by the United Farm Workers leader Cesar Chavez, who demanded a meeting with Gov. Edmund G. Brown to address farmworker conditions.
Since the latest march, U.F.W. members, along with other farmworkers supporting the bill, have held rallies in many California cities.
One morning this month, Amalia Rodriguez, 30, joined a dozen supporters of Assembly Bill 2183 outside a state building in downtown Los Angeles.
Ms. Rodriguez began working in strawberry fields in Oxnard, an agricultural community 60 miles northwest of Los Angeles, when she was a teenager. She said she had seen growers intimidate farmworkers, many of whom are undocumented.
“They tell us to be grateful for what we make and not be greedy,” she said.
“We are treated like we are nothing,” Ms. Rodriguez added, as fellow protesters shouted the union’s motto, “Sí, se puede” (“Yes, we can”), as passing cars honked in support.
“We work hard and are just told to be quiet,” she said.