SAN FRANCISCO — With tens of thousands of people living on the streets of California, the homelessness crisis has become the state’s defining issue. For Gov. Gavin Newsom, the emergency had become so dire that he devoted his entire State of the State address on Wednesday to the 150,000 Californians without homes.

“Let’s call it what it is: It’s a disgrace that the richest state in the richest nation, succeeding across so many sectors, is falling so far behind to properly house, heal and humanely treat so many of its own people,” Mr. Newsom told lawmakers in Sacramento. “Every day, the California dream is dimmed by the wrenching reality of families and children and seniors living unfed on a concrete bed.”

Vulnerable to the charge that the problem has exploded under Democratic rule in California, Mr. Newsom, a former mayor of San Francisco, pleaded with — and at times admonished — legislators to take action.

“The hard truth is for too long we’ve ignored this problem,” Mr. Newsom said. “We turned away.”

Homelessness has become pervasive in California, from the rural North to the sun-kissed coastal cities, and it has exposed the stark inequality in the state, whose economy would rank as the world’s fifth largest if it were an independent country. Living in the shadow of the biggest names in technology — just a few dozen miles from the campuses of Apple, Google and Facebook — are hundreds of clusters of homeless people, in makeshift compounds that resemble some of the world’s most destitute refugee camps.