The total number of job postings for the cannabis industry increased 445% in 2017, according to job-search website ZipRecruiter.

There are now more people working in the legal cannabis industry than there are dental hygienists in the US.

The legal cannabis industry could be a $21 billion industry by 2021.

The legal cannabis industry is posting some eye-popping job-growth numbers.

The total number of job postings for the cannabis industry increased by 445% in 2017, as a host of states — including Nevada and Massachusetts — legalized the plant for adult consumption. That's up from just 18% growth in 2016, according to a recent study from ZipRecruiter, an online job platform.

Nine states and Washington D.C. have legalized cannabis, though it's considered an illegal, Schedule I drug at the federal level.

Because of that trend, there are now more cannabis workers than dental hygienists in the US, according to Marijuana Business Daily, a financial-news publication focusing on the cannabis industry. The higher end of their estimate range suggests there were 230,000 people employed in the US legal cannabis industry in 2017, whereas there were 201,000 dental hygienists, according to the US Bureau of Labor Statistics.

Job growth in the cannabis industry is now outpacing some of the fastest-growing fields in the US, including tech and healthcare. Job postings in the healthcare industry grew 70% in 2017 while tech — defined as jobs in the software and IT space — rose by 254%, according to ZipRecruiter's data.

The pace of cannabis-industry job growth increased throughout 2017 as businesses went on a hiring spree to gear up for the start of legal sales in California, according to ZipRecruiter's chief economist, Cathy Barrera. (Marijuana became legal in that state on January 1.)

Cannabis jobs are mostly clustered in the industry's epicenters — Los Angeles, San Francisco, and Colorado, according to ZipRecruiter — as well as a few cities in Florida. Florida legalized medical cannabis in 2016.

A woman holds marijuana for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson

Cannabis could become a $21 billion industry

Consumers spent around $9 billion on cannabis in 2017, according to the industry research firm BDS Analytics.

Now that marijuana is legal in California — by far the most populous state to legalize the drug — the report predicts the state will pull in over $5.1 billion in cannabis sales in 2018. For comparison, Californians bought $5 billion worth of beer in 2017, according to industry research group IBIS World.

Total spending on legal cannabis is expected to skyrocket to over $21 billion by 2021 for all US consumers, the BDS report says. Factoring in "indirect effects" of legal cannabis revenue, such as transactions between cannabis companies and businesses in other industries (like shipping, packaging, payroll processing, etc.), BDS Analytics expects legalized cannabis to inject close to $40 billion into the US economy by 2021, and add up to 413,988 jobs.

The report, however, notes that forecasts about the cannabis business are difficult because its illegal status at the federal level means the federal government doesn't track data for the industry.

If marijuana were to become legal in all 50 states, a new report from cannabis industry research firm New Frontier Data estimates that the industry could add over $130 billion to US tax coffers by 2021. But that's only if Attorney General Jeff Sessions — a noted cannabis legalization opponent — doesn't pursue a federal crackdown.

Earlier this month, Sessions rescinded an Obama-era rule directing the Justice Department to leave state-legal cannabis businesses alone. That move may put the industry's future in jeopardy. A growing chorus of lawmakers on both sides of the aisle blasted Sessions' decision, though many leaders in the cannabis industry were unperturbed.

A majority of Americans support legalizing cannabis. Some 58% of voters said in a Quinnipiac poll earlier this month that marijuana should be legal, and 70% of voters oppose enforcing federal laws in states that have made marijuana legal.

Although President Donald Trump talked a lot about jobs in his recent State of the Union speech, his administration does not seem to favor policies that would boost job creation in several of the US' fastest growing areas: cannabis, solar power, and wind energy.