COSTA MESA, Calif. — In the forests of Northern California, raids by law enforcement officials continue to uncover illicit marijuana farms. In Southern California, hundreds of illegal delivery services and pot dispensaries, some of them registered as churches, serve a steady stream of customers. And in Mendocino County, north of San Francisco, the sheriff’s office recently raided an illegal cannabis production facility that was processing 500 pounds of marijuana a day.

It’s been a little more than a year since California legalized marijuana — the largest such experiment in the United States — but law enforcement officials say the unlicensed, illegal market is still thriving and in some areas has even expanded.

“There’s a lot of money to be made in the black market,” said Thomas D. Allman, the sheriff of Mendocino County, whose deputies seized cannabis oil worth more than $5 million in early April.

Legalization, Sheriff Allman said, “certainly didn’t put cops out of work.”

California’s governor, Gavin Newsom, has declared that illegal grows in Northern California “are getting worse, not better” and two months ago redeployed a contingent of National Guard troops stationed on the border with Mexico to go after illegal cannabis farms instead.