By latest count, some 109,089 people are sleeping on the streets of major cities in California, Oregon and Washington. The homelessness crisis in these cities has generated headlines and speculation about “root causes.” Progressives allege that tech companies have inflated housing costs and forced middle-class people onto the streets.

Declaring that “no two people living on Skid Row . . . ended up there for the same reasons,” Los Angeles Mayor Eric Garcetti, for his part, blames a housing shortage, stagnant wages, cuts to mental health services, domestic and sexual abuse, shortcomings in criminal justice and a lack of resources for veterans. These factors may all have played a role, but the most pervasive cause of West Coast homelessness is clear: heroin, fentanyl and synthetic opioids.

Homelessness is an addiction crisis disguised as a housing crisis. In Seattle, prosecutors and law enforcement recently estimated that the majority of the region’s homeless population is hooked on opioids, including heroin and fentanyl.

If this figure holds constant throughout the West Coast, then at least 11,000 homeless opioid addicts live in Washington, 7,000 live in Oregon and 65,000 in California (concentrated mostly in San Francisco and Los Angeles).

For the unsheltered population inhabiting tents, cars and RVs, the opioid-addiction percentages are even higher — ­Seattle’s homeless-outreach team estimates that 80 percent of the unsheltered population has a substance-abuse disorder. Officers must clean up used needles in almost all the homeless encampments.

For drug cartels and low-level street dealers, the business of supplying homeless addicts with heroin, fentanyl and other synthetic opioids is extremely lucrative. According to the Office of National Drug Control Policy, the average heavy-opioid user consumes $1,834 in drugs per month.

Holding rates constant, we can project that the total business of supplying heroin and other opioids to the West Coast’s homeless population is more than $1.8 billion per year.

In effect, Mexican cartels, Chinese fentanyl suppliers and local criminal networks profit off the misery of the homeless and offload the consequences onto local governments struggling to get people off the streets.

West Coast cities are seeing a crime spike associated with homeless opioid addicts. In Seattle, police busted two sophisticated criminal rings engaged in “predatory drug dealing” in homeless encampments (they were found in possession of $20,000 in cash, heroin, firearms, knives, machetes, and a sword).

Police believe that “apartments were serving as a base of operations that supplied drugs to the streets, and facilitated the collection and resale of stolen property.” In other words, drug dealers were exploiting homeless addicts and using the city’s maze of illegal encampments as distribution centers.

In my own Fremont neighborhood, where property crime has surged 57 percent over the past two years, business owners have formed a group to monitor a network of RVs that circulate around the area to deal heroin, fentanyl, and methamphetamines. Dealers have become brazen — one recently hung up a spray-painted sign on the side of his RV with the message: “Buy Drugs Here!”

What are local governments doing to address this problem? To a large extent, they have adopted a strategy of deflection, obfuscation and denial. In her #SeattleForAll public relations campaign, Mayor Jenny Durkan insists that only 1 in 3 homeless people struggle with substance abuse, understating the figures of her own ­police department as well as the city attorney, who has claimed that the real numbers, just for opioid addiction, rise to 80 percent of the unsheltered.

The consequences of such denial have proved disastrous: No city on the West Coast has a solution for homeless opioid addicts. Los Angeles, which spent $619 million on homelessness last year, has adopted a strategy of palliative care — keeping addicts alive through distribution of the overdose drug naloxone — but fails to provide access to on-demand detox, rehabilitation and recovery programs that might help people overcome their addictions.

The city has been cursed, in this sense, with temperate weather, compounded by permissive policies toward public camping and drug consumption that have attracted 20,687 homeless individuals from outside Los ­Angeles County.

No matter how much local governments pour into affordable-housing projects, homeless opioid addicts — nearly all unemployed — will never be able to afford the rent in pricy West Coast cities. The first step in solving these intractable issues is to address the real problem: Addiction is the common denominator for most of the homeless and must be confronted honestly if we have any hope of solving it.

Christopher Rufo is a contributing editor of City Journal, from which this column was adapted.