Behzadzadeh’s dogs were barking ferociously when he and his wife returned home from dinner late one night in September. They didn’t think anything of it, but several hours later, the couple heard noises in their house. Behzadzadeh gathered his wife and children in a bedroom and raced downstairs with a laser-sighted pistol. But the intruders were gone, along with his cellphone — and the satchel.

The robbery could have been a financial disaster. A month earlier, the Denver Fire Department had determined that the extraction room at Avicenna was not sufficiently blastproof, shutting down the factory for two months. “If they had taken $30,000 or $40,000,” Behzadzadeh said, “it would have literally broken my back.” But the satchel held no money that night. Behzadzadeh had opened his bank accounts the morning after the inspection. It had taken him a few months to fully embrace them — Seefried had predicted as much — but now around two-thirds of his trading partners also accept or write checks. What cash remains in Behzadzadeh’s business waits in safes, secured to the floor, for the armored truck.

Yet despite Safe Harbor’s efforts and those of its competitors, bank accounts remain out of reach for many Colorado marijuana companies. The high fees put off smaller businesses at the same time as banks seem to be pulling back. Seefried didn’t want Safe Harbor deposits to swamp the credit union, so last January she reduced the number of new monthly clients from five to three and then closed the door altogether in August after deposits ballooned over the summer. As the state Marijuana Enforcement Division granted licenses to about 220 additional companies last year through November, Safe Harbor’s waiting list swelled to 96 businesses, or two-and-a-half-years’ worth of new clients, before the credit union stopped adding names to it. The five banks have become very stingy about granting new accounts, according to three C.P.A.s who have marijuana-industry clients. The parent company of one of those institutions, Colorado National Bank, declared bankruptcy in November, putting its future as a marijuana banker in doubt.

Marijuana banking has always depended entirely on forbearance from Washington, and the Trump administration seems decidedly less tolerant than its predecessor. In March, Attorney General Jeff Sessions declared before a gathering of law-enforcement officials that marijuana is “only slightly less awful” than heroin. “I reject the idea that America will be a better place if marijuana is sold in every corner store,” he said. A task force assembled in February by the Justice Department to combat violent crime didn’t recommend any changes to the Cole memo when it delivered its initial findings last summer, but the agency is very likely revising it. (The Justice Department wouldn’t comment on its deliberations.) [Update: After this article went to press, the Justice Department rescinded the Cole memo, giving U.S. attorneys more latitude to enforce federal marijuana laws in their districts.]

Seefried had hoped to begin making loans to and processing credit-card transactions for Safe Harbor’s existing clients, but for the foreseeable future, she has put those plans on hold. Until federal law catches up to public sentiment, marijuana banking is unlikely to keep pace with the industry — the vetting is too expensive. Just last month, after a client was caught up in a police investigation, Safe Harbor had to review the account to make sure bankers hadn’t missed any suspicious activity. “It cost me $30,000: $20,000 to bring in investigators for three days and $10,000 for legal fees,” Seefried told me. “That’s one client, with one problem.” She plans to raise fees in the next couple months.

Yet she still hopes to position Safe Harbor as a model for banking the marijuana industry elsewhere. In November, Safe Harbor began licensing its name and protocols to financial institutions nationwide. Six banks and credit unions in six states will begin taking on customers this month, including a credit union in Colorado to serve the customers that Safe Harbor no longer can. Three more will join each quarter. Safe Harbor is also testing a mobile-phone app for buying marijuana in Hawaii’s handful of state-licensed dispensaries.

In June, the National Credit Union Association, Partner Colorado’s regulator, advised Seefried that it would begin examining the institution quarterly rather than yearly, which she attributes to the national expansion. She has hired two full-time employees just to manage the increased compliance. “We are bringing more credit unions to the table, and they don’t want us teaching them incorrectly,” she says.

One industry investment facilitator, the Arcview Group, estimates that legal marijuana sales in the United States will more than double to roughly $21 billion by 2021 from nearly $9 billion last year. Walsh, the former prosecutor, has concluded that the tension between the federal government and liberalizing states is unsustainable. “I came in as U.S. attorney in 2010 assuming that it was my job to enforce the federal marijuana laws regardless of what state legalization efforts would look like,” he says. “The longer I worked on the issue, and we struggled with it, the more I realized that a simple shut-it-down approach was not practical. The notion that you can put this genie back in the bottle today is not realistic.”