Drive along any major roadway in Maine and you’re apt to see them. They are usually long metal buildings with numerous sliding garage-style doors that sometimes take up acres and are rented by people to store all kinds of stuff.

The storage units are a real breadwinner for their owners, which helps explain why they’re popping up all over the landscape.

There are a number of self-storage facilities scattered in and around Bangor. Forty-three are listed in the Bangor area phone book and the number of units keeps growing, said city Code Enforcement Officer Dan Wellington.

“We have four facilities here in Bangor with three that have been built in the last decade,” Wellington said recently. “One is contemplating adding another couple units.

“They have become immensely popular,” he said. “I’m not sure if it’s because in our society we gather a lot of property, but it’s quite a phenomenon. If you drive down to Boston they pepper the communities along the highway.”

Wellington and several owners of storage units in the area say they haven’t had any major problems with people using the facilities for illegal purposes.

“We have never had any bad experiences here,” Wellington said. “People have been found living in these units [in other parts of the country] and people have rented under assumed names for the express purpose of getting rid of hazardous materials. We’ve never had any incidents here where hazardous or inappropriate materials have been found.”

A quick search of the Bangor Daily News archives, however, revealed several instances where storage units in Maine have been used for less-than-legitimate purposes. In March of this year a former Dixmont man was charged with criminal use of explosives after homemade bombs and illegal fireworks were found in his self-storage unit in Palmyra. In June of last year a Maine couple were arrested in Arizona after a search of their storage unit in Wells turned up illegal drugs and paraphernalia associated with trafficking. During the same period last year a Bangor resident was arrested for storing in his Eddington unit 58 grams of crack cocaine, the largest known seizure of a cocaine base in the Bangor area to date.

And during October of last year, Theodore Miller of North Amity was indicted on charges of possession of firearms and ammunition after a search of his Orono storage unit turned up 18 rifles and shotguns. Secret Service agents originally investigated Miller after he arrived in Kennebunkport, near the home of former President George Bush, four days before President George W. Bush was to arrive.

“He had threatened the president in Kennebunkport, and the Secret Service came in with a federal search warrant and took out 18 guns that they confiscated,” said the owner of the facility, who asked to remain anonymous. “The guy is in federal prison but he’s paid his rent here, or his mother has. You don’t know what’s [left] in the building because the renters have the key.”

For the most part, however, storage units are used by people moving in or out of the area who need to store furniture for a while. They are used by folks parking boats and campers during the winter. They act as an extra attic for people who don’t have enough space in their homes or apartments for their unused exercise equipment or clothes. Some businesses use the facilities to store extra inventory and office equipment. And college students often store furniture, books and other items during the summer break.

Joe Cushman, owner of Maine Self Storage on Outer Hammond Street in Bangor, said one of his units was even used by law enforcement officials to store potential evidence.

“We did have something that may be used in a trial as evidence by the attorney general,” he said, but he would not elaborate on what that evidence was.

Most of the time, though, Cushman said he doesn’t see what people place in the units.

Former Hampden resident Mark Belanger remembers practicing with his band in a unit at Ammo Self Storage on Odlin Road. He said the band was the only one that rehearsed at the facility. However, once he moved to Portland the band, Broken Clown, wasn’t alone.

“There were a whole bunch of bands that would practice down there at Cumberland Self Storage on Commercial Street,” he said. “They had rooms that were big enough for four people and their equipment to rehearse in. At the one in Portland there was a guy living there.”

At Orono-Old Town Self Storage, which is the closest storage facility to the University of Maine, no bands are allowed to rehearse, but there have been requests, said owner Al Richard.

The price for renting storage space around Bangor starts at about $25 a month and runs to about $135 a month.

The oldest running self-storage facility in Bangor is U-Haul Co. on Summer Street. Wellington said Bangor’s U-Haul has always “offered some inside units. They’re like large inside closets.”

Nowadays, people can rent a variety of different sized storage units, indoors and out.

Some storage units around Bangor have electronic security and others just have locks provided by the renters. Some are fenced and lighted, others have keypunch entry or security cameras and still others are even climate controlled.

Cushman claims his Maine Self Storage is Bangor’s biggest such facility.

“We have 350 units,” he said. “We’ve got about 46,000 square feet. We’re at the point that our next permit would be like Wal-Mart’s.”

Cushman’s smallest unit is 5 feet by 5 feet and the largest is 10 feet by 30 feet. He said his facility, which has been open for five years, is often used by commercial businesses that take up more than one space.

“There were three or four [storage businesses] in the area when I started and now they seem to be everywhere,” he said.

The return on the investment is a major reason for building the business, said Cushman. Overhead costs are fairly low and demand is high. He said many of the people who rent units are new to the area.

“You’d be surprised how many [people] come in and store stuff without a house or a job,” he said. “We’ve got a lot that come in that way.”

Military personnel are another group that uses units, especially when they are stationed overseas, said Mark Cushman, Joe’s son and the manager for Maine Self Storage. He said classic cars are another big storage item.

“We’ve had the hospital store extra supplies here and we’ve had a couple people rent storage units for six months because they’re hiking the Appalachian Trail,” he said.

Former Bangor resident Michele Barker, who was emptying her storage unit at Maine Self Storage last month, said she rented the unit to store her belongings during the transition time between her move from Bangor to New Hampshire.

“I have my whole apartment in here,” she said. “I have my couch, bed, entertainment center, TV, furniture and all the kids’ stuff, plus a lot of books. I’ve had it since March. We’re slowly cleaning it out.”

Proximity to Interstate 95 was the reason Barker chose the self-storage facility.

Joe Tyler, owner of Tyler’s Self Storage on Stream Road in Winterport, has 23 units at his facility, which is located directly beside Tyler’s Garage. He said he got into self-storage three years ago.

“I figured it was something good to get into,” said Tyler, who uses one of the units for himself. “It’s just something I was going to do four or five years ago.”

Units at Tyler’s range from 5 feet by 10 feet to 10 feet by 20 feet.

“They run anywhere from $35 to $85 per month,” he said, adding that summer and fall are his busiest seasons.

Renters are responsible for insuring the contents of their units, said Tyler, but he said his business has never had any problems with vandals.

Contracts for storage units are usually month to month. Failure to pay can result in severe penalties and loss of property, said Bob Bemis, owner of Union Street Self Storage in Levant, who said he’s never had any renters fail to pay for their storage.

“If they don’t pay their bill, first they get a late fee,” said Bemis. “If they don’t pay it within 30 days we apply an overlock, and if they don’t pay then, we start disposal procedures, which are established by the state.”

State law considers the property abandoned after 30 days of nonpayment and allows the storage facilities to sell items left in the units after placing a public notice in a local newspaper at least three weeks before sale.

Bemis, still in his first year of business, said he hasn’t had to hold an auction yet. Tyler said in the three years he’s been operating his storage business, he hasn’t had to pursue collections, and Mark Cushman said there have been no auctions with his facility, either.

“It’s never happened to me so far,” Tyler said. “Usually, I try and notify them and they show up and catch back up.”

Despite the number of facilities that has cropped up in recent years along Maine’s highways, the demand for storage units continues to grow.

“The supply has never caught up with the demand,” said Wellington. “I don’t see any reason or indication that the market demand has been filled. What we hear is that they’ve got waiting lists. The market is there and as soon as we finish one of them, we hear it’s full.”