The benches and bar stools fill quickly on evenings when the Borderlands Brewing Co. opens its tap room, a rustic, exposed brick building downtown in Tucson's historic warehouse district.

Once a depot for train-delivered produce, the space is now home to one of the city's most popular microbreweries.

Five craft beers, all created by Borderlands staff, are served three nights a week to patrons who socialize at communal tables while downing pints from the bar and nachos from the gourmet Mexican-food truck in the parking lot.

There's regular live music and it's a hoot to feel your teeth rattle as trains rumble by just beyond the building's back windows.

Of course, the beer is the big draw.

"It has been amazing," said Myles Stone, who opened the brewery eight months ago with his partners Michael Mallozzi and Blake Collins. "There hasn't been one batch of beer that we've made that hasn't sold out two to three days before the next batch was ready."

Borderlands is riding the wave of what has become a craft-beer industry boom in the United States with nearly 2,000 brewpubs, microbreweries and regional craft breweries operating across the county, according to the national Brewers Association.

In Arizona, the number of operating microbreweries has increased to 52 from 35 in the last two years, said Lee Hill, Arizona Department of Liquor spokeswoman.

Microbreweries with active licenses in Pima County have jumped to seven from four since August of last year.

Two more breweries, the Corbett Brewing Co., which wants to open next to the Ordinary Bike Shop near North Fourth Avenue and the Sentinel Peak Brewing Co., at the old Farmer John meatpacking plant on West Grant Road, have licenses pending.

"Craft beer sales are up," Hill said. "It is one of the fastest growing liquor industries in the country, followed by wine."

Microbreweries in town are being encouraged by the increasing number of bars and restaurants eager to carry the homespun creations, as well as events such as the Great Tucson Beer Festival on Oct. 6, and the inaugural Born & Brewed Tucson Beer Cup challenge at Hotel Congress this weekend.

Some startup breweries, like the Dragoon Brewing Co., 1859 W. Grant Road, have risen fast.

Owner Bruce Greene and his son Eric Greene, the head brewer, sold their first keg in April. Today, they have 41 accounts at bars and restaurants across Tucson and Phoenix.

"I think it speaks to how Tucson businesses are looking for good, quality local products," said Eric, who works six days a week in Dragoon's 5,700-square-foot warehouse space.

The microbrewery tries to have at least four beers available at all times.

Its strong, hoppy Dragoon India Pale Ale and its toasty Stronghold Session Ale are on tap year-round.

The other two specialty beers rotate, depending on the season and the whim of the brewers.

The company ships most of its product - about 465 gallons for every batch made -out the door. Some stays in house for its tap room.

Eric Greene, a graduate of the American Brewers Guild in Vermont, has worked with the homebrew company Mr. Beer, as well as Nimbus Brewing Co. He said Dragoon hasn't made money yet because it had to buy additional equipment to keep up with demand.

While longtime residents of Tucson, he said he and his father looked at several markets, places such as Denver and San Diego, before opening in town.

"We saw the kind of beer people were buying at places like Plaza Liquors and thought that Tucson had potential," he said. "We took a gamble that Arizona and Tucson in particular was ready to support more craft beer."

Eric Greene said longtime local breweries, Thunder Canyon, Nimbus and Gentle Ben's, have helped to lay the groundwork for newer breweries.

Thunder Canyon owner Steve Tracy and Dennis Arnold from Gentle Ben's and Barrio Brewing even provided advice and direction as the Greenes were getting started.

"So far, there isn't a lot of competition," Greene said. "Some people raise their eyebrows at whether or not the spirit will continue. I think it will."

Greene said the short-term goal is to expand production and equipment - more giant fermenters and other larger-than-life beer-making components - to get more kegs out the door.

Downtown, Borderlands also plans to expand.

The brewing company is still in its "soft opening phase" said Stone, a medical student who divides his time between conducting rounds at the University of Arizona Medical Center and serving rounds of beer at Borderlands.

Right now, the company has the smallest tanks a microbrewery can have, which produce around six kegs per batch.

Aside from its downtown space, Borderlands beer is available in only three other locations: the Loft Cinema, the Dry River Co. on North Kolb Road and Monkey Burger, downtown.

"In theory, we are a wholesale brewery," Stone said. "In reality, we keep running out of beer. We've kind of become just a bar with really bad hours."

By November, Stone said Borderlands will have much larger tanks, upping its production to 40 kegs a batch.

Stone said the money for the tanks is coming from the profits made from beer sales, as well as from investors who believe in the notion of more craft beer for Tucson.

"Right now we are self-sustaining," Stone said. "People seem to enjoy what we are doing."