California's Bureau of Cannabis Control has issued a notice stating that billboards advertising cannabis must come down.
The requirement applies to any cannabis billboard ads on interstate highways and on state highways that cross the California border.
This comes after a San Luis Obispo County Superior Court judge ruled they are illegal under Proposition 64.
The notice states, "To comply with the law and regulations, licensees may not place new advertising or marketing on any interstate highway or state highway that crosses the California border. Licensees should also begin the process of removing current advertising and marketing that meets this criteria."
It means billboards will not be allowed on 35 highways in California, including Highway 101.