It took less than a week for the Trump administration to kill the considerable buzz created Jan. 1 when California's broad marijuana legalization law took effect, creating the largest legal U.S. cannabis marketplace.
Then-U.S. Attorney General Jeff Sessions rescinded a policy shielding state-licensed medical marijuana operators from federal drug prosecutions.
The move sent a chill through the nascent legal industry. But ultimately it had little impact because federal prosecutors around the country showed little interest in going after legal operators.
Sessions, a staunch marijuana opponent, later lost his job and the cannabis industry thrived in a hugely significant year for the legal pot movement, in the United States and beyond.
Here are some highlights:
— Jan. 1: California's law takes effect, allowing people 21 and older to use marijuana.
— Jan. 4: Sessions rescinds policy.
— Jan. 22: Vermont's Legislature legalizes recreational marijuana. It's the first time a state legislature, rather than voters, approved such a law.
— June 25: U.S. health regulators approve the first prescription drug made from marijuana. The medication, Epidiolex, is used to treat two rare forms of epilepsy in young children.
— June 28: Oklahoma becomes the 30th state to legalize medical marijuana use.
— July 19: A Canadian company, Tilray Inc., is the first marijuana business to complete an initial public offering on a major U.S. stock exchange, raising $153 million as it began trading on the Nasdaq exchange.
— Aug. 15: Constellation Brands Inc., the parent company of Corona beer and other alcoholic drinks, makes a $4 billion investment in Canopy Growth Corp., a major Canadian pot producer.
— Oct. 17: Canada legalizes marijuana use for people 19 or older in most provinces. It's the second country after Uruguay to legalize marijuana, and its First-World nation status adds greater credibility to the global marijuana marketplace.
— Oct. 31: Mexico's Supreme Court rules individuals can use marijuana under their right to decide their own recreational activities. The decision puts the country a major step closer to broad legalization.
— Nov. 7: Voters make Michigan the first Midwestern state and 10th overall to legalize recreational marijuana use. Missouri and Utah approve medicinal marijuana.
— Nov. 20: Massachusetts' first commercial pot shops open, more than two years after voters in the state approved of recreational marijuana for adults. The stores are the first to operate on the U.S. East Coast.
— Dec. 7: U.S. cigarette maker Altria invests $2.4 billion in Canada marijuana company Cronos Group.
— Dec. 10: New Zealand passes a law making medical marijuana widely available. A nationwide referendum on recreational pot is planned within two years.
— Dec. 20: President Donald Trump signs into law a farm bill that removes hemp, the cannabis plant cousin to marijuana, from the list of federally controlled substances.
— Dec. 25 — Thailand's legislature amends the country's drug law to allow the licensed medical use of marijuana.
— Dec. 25 — Israel's Parliament approves a law to permit exports of medical marijuana.