Tucked on a side street, behind a restaurant just off Interstate 394 in Golden Valley, sits a nondescript boxy building that spans several blocks.

Step inside, and huge plumes of steam and cornstarch dart to the rafters as a massive “corrugator” stamps, slices and glues 8,000-pound paper rolls into thousands of shipping boxes and product displays destined for Amazon, Heineken, Owens Corning, the Red Cross, Hormel and groceries nationwide.

The bustling Liberty Carton is just one page of Liberty Diversified International (LDI), a $675 million company determined to grow ever larger by adding more corrugated-board customers and acquisitions.

“Our packages could be in every store in America and are in every phase of your life,” LDI CEO Mike Fiterman said. “They display your fruit, deliver groceries to stores, and ship your diapers, furniture, television sets and the tile in your basement. … And to think, it all started with my grandfather and a horse and a wagon” in 1918.

If you have never heard of the 100-year-old company, you are not alone. But it’s roughly the size of Marvin Windows, with similar fourth-generation ownership and ubiquitous products.

“It’s a very tight, family-owned business, and they just don’t share a lot of data,” said Bob Kill, CEO of the consulting firm Enterprise Minnesota. “They’ve done a remarkable job of making sure no one puts their pieces together.”

Nationally, LDI owns eight companies that each operate under a different name. It boasts 1,800 workers, 14 factories and $675 million in combined 2017 sales. Earlier this month, it continued its quest for acquisitions, buying Preferred Packaging and Container Inc., in Phoenix for an undisclosed price. The 70-employee firm is one of a series of purchases that have stretched LDI from coast to coast and from Minnesota to Mexico.

Fiterman is the quiet force behind the growth. He joined the company in 1970 and took over as CEO from his father, Benny, in the 1980s. Also running the company: Fiterman’s son Jack and one of his daughters, Ann Miller.

Based in New Hope, LDI has 728 Minnesota workers between its paper mill in Becker and manufacturing plants and offices in New Hope, Golden Valley and Brooklyn Park. Its other operations span from Virginia to California and Mexico.

“We are on the road to $1 billion [in sales] in the next four to five years through acquisitions and organic growth,” Fiterman said.

After many acquisitions 12 years ago, the family recently reorganized the company into three units that are “much more focused,” said Jack Fiterman, strategic accounts and new products director.

Office and school furniture result in 20 percent of sales. Roofing and building materials contribute 10 percent. But it’s the corrugated box and carton business that continues to drive 70 percent of all sales, winning fans among customers and state officials alike.

“Their point-of-sales displays are amazing,” said Wayne Gjerde, recycling market development coordinator for the Minnesota Pollution Control Agency. He has been impressed by LDI’s flattened boxes and tabs, which suddenly unfold like a tethered jigsaw puzzle and refit into new configurations that display goods or protect them during shipping.

“They can make anything for a display,” Gjerde said. “They are very talented.”

Gjerde first came to know LDI because of its recycling might. LDI’s massive 240,000-square-foot Liberty Paper mill in Becker uses automated equipment and 150 workers to convert 500 tons of waste paper each day into pulp and paper worth millions.

“They are a very important local market for us in Minnesota,” Gjerde said. “They buy local recycled paper and [turn it into] liner board for the corrugated paper industry. As a result, they have a wide range of customers,” such as Pearson’s Candy, Owens Corning and the products wholesaler SP Richards Co.

The paper mill in Becker has allowed LDI to control its paper costs, contributing to the company’s success, said Enterprise Minnesota’s Kill.

“A number of years back, they decided that they wanted to diversify and went off and bought a number of manufacturing companies,” he said. “But after awhile they kind of decided, ‘Maybe we should focus on adding value to the business that we know best, which is corrugated paper … and integrating vertically.’ ”

LDI is still acquiring firms, but this time it’s adding small companies with long histories in paper. “We want to grow,” Fiterman said. “If you don’t grow, you will probably disappear. Costs go up, so you have to have more revenue to spread across the operation.”

Beyond growth and acquisitions, Fiterman admits concern about new steel trade tariffs plus possible tariffs on Chinese imports that could be imposed by President Donald Trump.

“Who knows how this new trade dispute with China will affect us all?” he said. With all these concerns, “you have to get more efficient. And one of the ways we are growing is acquisitions.”

A year ago, LDI bought Miller Container Corp. in Illinois. In 2016, it acquired Western Container’s corrugated box and packaging division in Minneapolis and the Omaha Box Co. in Nebraska. In 2014, LDI bought Harbor Packaging Inc., with plants in San Diego and Tijuana and Mexicali, Mexico.

Kill said each deal diversified LDI geographically and expanded its workforce and sales faster than organic growth could.

The strategy also helped LDI obtain workers at a time when it has been hard to find new hires, Fiterman said.

LDI has created internships, hosted manufacturing recruiting events and partnered with area schools and colleges to get a younger generation to give manufacturing a try. It also developed a leadership-training program.

“We will need more people, so we need to find new ways to attract people to our business,” Fiterman said.

He’s not relying on recruiting alone. LDI is simultaneously investing in automated equipment.

“We have to invest in our capital expenditures like never before,” Jack Fiterman said. “There’s $30 million to $40 [in] million costs that need to be invested in the equipment” of several of the older companies LDI is buying. “From an acquisition standpoint, there are a lot of opportunities out there right now.”

The need to upgrade machinery is one reason many older box makers look to sell, he said.

For example, the Omaha factory LDI bought in 2016 had $25 million in annual sales. That’s the same amount LDI will spend modernizing machinery this year.

Mike Fiterman said LDI must spend the money to make the plants more efficient. A few weeks ago, LDI installed a new $4.5 million machine in its Brooklyn Park plant. “It changed our setup time from 30 minutes to 3 minutes,” he said. “When our customers see that, they get excited.”