Cannabis is illegal as far as the federal government is concerned.

California, Nevada, Oregon, Alaska, Washington and Colorado voted to legalize it, which means the local and state police won't arrest growers.

However, the federal police agencies (FBI, ATF, etc) can arrest anyone involved with cannabis if they want to. It all depends on the person currently giving them their orders - in this case attorney general Jeff Sessions. He insists that cannabis is illegal everywhere in America. “Good people don’t smoke marijuana,” he said in 2016. Sessions has been on a lifelong crusade against weed, and considers it the root of society’s ills.

Sessions just introduced new guidance on marijuana that makes it easier for prosecutors to arrest people using federal laws in states where cannabis was legalized. He wants prosecutors to ignore state law.

“It is the mission of the Department of Justice to enforce the laws of the United States, and the previous issuance of guidance undermines the rule of law,” he said in a statement. In his memo to United States attorneys, he called the earlier policy “unnecessary” and pointed to federal laws that “reflect Congress’s determination that marijuana is a dangerous drug and that marijuana activity is a serious crime.”

Senator Cory Gardner of Colorado threatened to retaliate against Sessions by holding up Justice Department appointments that require Senate approval. Gavin Newsom, the lieutenant governor of California, vowed to encourage cooperation among states that have legalized marijuana. “This brings states together around issues of freedom, individual liberty, states’ rights,” he said in an interview, “all of the principles that transcend red and blue.”

Banks say they will not offer any new loans to landowners whose properties have a pre-existing lease with a marijuana business. They've told commercial loan clients they’ll have to either evict the marijuana business or refinance their loan elsewhere because cannabis is illegal under federal law.

The banks won't take the risk because the property is theoretically subject to federal drug-seizure laws. Meaning they could lose their whole property if the government decides to crack down.

Without access to banking services, weed businesses are forced to do everything with cash, including driving hundreds of thousands of dollars (in 20 dollar bills) to the IRS to pay their tax bills. Which is an extremely dangerous thing to do because they could get robbed or worse.

However there is good news:

https://www.thecannabist.co/2018/01/31/california-marijuana-bank-taxpayer-backed/97917/

California is interested in starting its own bank to bypass national banks that fear the federal government. It'll take a year for them to complete the study to decide if it will go forward.

Growers say they live constantly with shifting legal terrain, losing their bank accounts and lines of credit and never knowing how vulnerable they may be to losing their business or being federally prosecuted. All of this adds up to making the weed business very high risk.

It's not, in my state.