OAKLAND — Roughly 3,000 people flocked to the Marriott Oakland City Center this week for a business conference that, in many ways, was just like any other. Businesses set up booths in a vast expo room, and business executives hosted panels about marketing, funding, business policy and leadership.

Unlike the countless other business summits that come to the Bay Area each year, every one of these attendees and presenters wanted to talk about marijuana.

Welcome to the largest cannabis business summit in the country. The Cannabis Business Summit and Expo, hosted by the National Cannabis Industry Association, is in its third year but first in the Bay Area, having touched down in cannabis-friendly Denver the past two years. It runs through Wednesday.

“It’s reflective of the historic role that California will be playing (in this industry) and the excitement for the potential,” said Taylor West, deputy director of the association, of moving the conference to Oakland.

After years of thriving in a hazy legal climate, the marijuana industry has emerged as something decidedly professional in California. That tone was evident at the business summit, where Lt. Gov. Gavin Newsom and Oakland-based Numi Tea founder Ahmed Rahim gave keynote addresses to attendees, many of whom paid $695 per ticket to get in the door, dressed up in suits.

And despite its still-gray laws regulating the sector, the Bay Area has become a hub for businesses of all kinds related to marijuana and solving business problems in the industry.

That was evident in the variety of businesses represented at the conference. Lawyers specializing in the fragmented landscape of cannabis regulation, insurance companies, equipment providers, investment companies and marijuana-infused food and product businesses were in attendance, networking with colleagues from all over the country.

“No longer does the idea of a stoner in the basement come to mind when our industry steps out of the shadows,” said NCIA director Aaron Smith, addressing several hundred of the conference’s attendees in a speech.

Indeed, after California became the first state to legalize marijuana for medical use in 1996, lobbying efforts have made medical cannabis legal in 25 states and Washington, D.C. California itself saw medical cannabis sales of $2.7 billion in 2015 — 62 percent of the country’s total sales, according to cannabis market research firms New Frontier and ArcView Market Research.

The high-powered business of marijuana is gaining steam in California. A new state law allows medical marijuana businesses to turn a profit and lifts the limit on how many plants a farmer can grow. At the same time, people are hopeful about the opportunity to approve recreational marijuana use statewide, which will be on the ballot this November.

Newsom, at the conference, spoke enthusiastically about support for the initiative, known as the Adult Use of Marijuana Act, or AUMA, citing the “failed war on drugs” that has led to an excess of people incarcerated for drugs and the benefit of economic development opportunities for municipalities throughout the state that support “responsible” marijuana businesses.

As efforts to legalize medical marijuana multiply across the country, businesses are benefiting from a certain legitimacy and reputational boost. Recently, that has been helped by tech giant Microsoft’s entry into the industry via a partnership with KIND Financial, a software provider that helps state and local governments track the cannabis business.

Creating standardization of product is also helping businesses gain legitimacy. Sage Analytics, a company from St. Louis attending the Oakland conference, helps cannabis producers measure the potency of their products, something that will help businesses keep up with regulations as laws change, said Jason Lupoi, director of scientific applications for Sage.

Conferences like the one in Oakland also could help change the business — and perception — of marijuana.

Eric Zetlin, who was attending the conference as a representative of California-based MJ Dispensing Solutions, which provides technology for banking and credit card processing in the marijuana industry, said many are surprised at how professional the network of marijuana businesses are.

“My first (marijuana business) conference was in Las Vegas, and I was amazed,” he said.

Contact Annie Sciacca at 925-943-8073. Follow her at Twitter.com/AnnieSciacca.