CASPER, Wyo. — Tonight the streets of Casper are quiet. Old ice is frozen against the curbs. Snow clumps around the lamp posts and melts into puddles. A few cars roll through downtown. Small groups of people walk huddled under the chipped brick of buildings and Western signs. The storefronts are dark, but the bars downtown are warm and glow through the windows.

The World Famous Wonder Bar is among them, advertising dollar "old school" beers in its lighted billboard and Monday Movie Day showing "Ferris Bueller's Day Off." This is the local hangout, where oil workers go in their new pickups, Fords and Chevys, a place for after-work beers and talk. Inside it's a ruckus.

Outside, and beyond the downtown on the outskirts of this town, known as "Oil City," it's a blur of chain stores and restaurants. There are Outbacks and Applebee's, Walmarts and Targets, Starbucks and shopping centers, all speckled with Days Inn, Ramada, Best Western and Marriott hotels. Beyond these and the four large golf courses in Casper twinkles the Sinclair Oil Refinery, where trucks stand waiting to transport the petroleum, the source of the region's wealth.

It's the kind of oil-driven economic activity and abundance that Greeley and Weld County hope to see in the years ahead. Thanks to the emerging boom in the Niobrara shale formation, the region already is seeing lower county property taxes, added employment, revitalized roads and additional funding for education, such as for Aims Community College.

Yet — as anyone who has lived in Casper can tell you — with every oil boom there is a bust, a downfall that's not a matter of "if," but when. And you'd better plan on it.

There are lessons to be learned from Casper and other oil towns that have been through this cycle before, but it remains to be seen whether they're being heeded. This much is clear: Weld's addiction to oil dollars is growing. Oil and gas already account for 45 percent, or more than $172.4 million, of Weld's property tax revenues. Some school districts depend on oil and gas revenues for much of their funding.

Among the questions for Greeley and Weld residents: What happens if oil activity dries up? Will schools, homeowners and others be left high and dry? Or will the Niobrara continue to pump prosperity into the region for decades to come?

Back at the Wonder Bar, it's 7:30 on a Wednesday night and the bar is packed. "American Woman" is blaring in the background. Casper residents, such as the Wonder Bar's Amy Frontiero, know the highs and lows all too well.

When the price of oil goes down, production goes down, too, then jobs. Casper, an epicenter of infrastructure with discoveries dating back to the 1800s, knows the struggle. Here families can measure joy and sorrow, not just by the moment, but by the barrel.

Frontiero works the bar tonight. She serves up Budweisers and glasses of Jim Beam. She moves quickly, takes orders while making conversation, three glasses in one hand and a bill in the other. Oil, she said, has been providing customers ever since she can remember, and tonight is no different.

Oil, she says, is the town and sacrifices " great and small " are made to keep it going.

"People have missed deaths in their families. People have missed being able to go to weddings. You hear a variety of stories," Frontiero said. "We actually had a guy in here a couple months ago that missed the birth of his child. But times being the way they are, it's not like he can just drop what he's doing and just go home."

The oil workers come and go in rotations, some for one week, some for two weeks, some permanent and others part of the industry, selling motors, pumps, whatever is needed, she said.

"You see the guys who are away from their wives, the guys who are still very young and are looking for girlfriends," she said. "You see the people who miss their children. It's just like having a long-distance family that comes back and forth."

There are major differences between Greeley and Casper, Weld County and Natrona County. For starters, Greeley's population of more than 92,000 is nearly double Casper's of about 55,000; Weld has about 253,000 people to Natrona's 75,000. Also, Greeley and Weld have well-established industries and strong agricultural roots. Casper and Natrona are much more dependent on oil and gas. From 2001-11 oil and gas property tax revenues averaged about 44 percent per year of Natrona County's total property tax revenues.

Yet, every day, Greeley and Weld find themselves leaning more and more on oil and gas money.

From 1981 to 2003 Weld's oil and gas property tax revenues " where Weld receives direct funding from the oil and gas industry " fluctuated between about 21.5 and 35 percent of all county property tax revenues, averaging 25.8 percent.

By 2004, the percentage of oil and gas revenues in the county's budget climbed to 32.4 percent of all property tax revenues. It peaked at 49.7 percent in 2009 " roughly $192.2 million. According to Weld assessor records, the county assessed oil and gas properties at $623.3 million in 2001, and most recent data in 2011 showed a rise to about $2.44 billion.

Currently, property taxes " including revenue from oil and gas " provide about one-third of the money Weld generates and account for the largest source of income for the county.

The Niobrara play in Weld fuels the revenue rise, coupled with hydraulic fracturing and horizontal drilling, two oil extraction processes that have made previously inaccessible shale a more profitable target.

According to the Colorado Oil and Gas Association, estimates vary, but the Niobrara potentially contains about 1 billion barrels of recoverable oil. Weld County Commissioner Sean Conway said he's been told by industry experts this means about 50 years of future oil development for the county.

However, despite the sweeping influence on Weld, the county still has a long way to go before it becomes as dependent on oil as Natrona.

Mining " which includes the oil and gas industry " represented only 8 percent, $590 million, of Weld's total Gross Domestic Product of roughly $7.34 billion in 2010, according to the U.S. Department of Commerce's Bureau of Economic Analysis. Manufacturing " Weld's largest industry " represented $1.12 billion, or 15.25 percent, of the county's total GDP in 2010. GDP measures the total value of goods and services.

Mining in Natrona represented 42.1 percent, about $2.87 billion, of the county's total GDP of roughly $6.8 billion.

And yet, the GDP also shows the bulging economic muscles of oil and gas in Weld. In 2001, Weld's GDP from mining stood at $102 million. By 2010, it totaled $590 million " an increase of more than 578 percent.

Oil can be a game of red light, green light, moving and stopping. This is the way Natrona County Commissioner Ed Opella tells it.

In the boom years, money spreads. The bars and restaurants, hotels and apartments fill in. New homes, new roads emerge. Schools and prisons are expanded or built. Ambitious county projects are drafted, then break ground. Workers from out of town are brought in to fill the demand. A seller's market hits real estate because rentals are in short supply. The roads brighten in the shine of new cars coasting down the highways.

In the bust years, everything is bleak and hopes dim. The economy screeches to a lethargic halt. Dark storefronts spread through downtown, the streets empty out. Grand ideas are put on hold, reduced or dumped. Oil rigs and gas pipes rust in the fields. Families leave town. Foreclosures rise. Homes and buildings sit vacant. The county trims the ranks of its employees. Unemployment shoots upward. And the family providers, once earning thousands, are left with minimum wage or no wage at all. Yet the bars, they're still full, but this time for different reasons.

"When oil stops, everything stops," Opella said. "I used to be in the pump business, that was my business. And everybody fixes pumps when things get bad. They lay off people when things get bad. Most people leave town because they need work. Then there's vacancies in apartments ... It's a ghost town figuratively speaking."

When so many people and sectors in society " real estate, school districts, businesses and government " are so dependent on energy revenues, there's only so much that can be done to prepare for a downturn or bust, Opella said.

"You just react to it when it happens. The same as when it goes up, as when it comes down," Opella said.

Despite the obstacles, Opella said the county tries to be as conservative as possible in the boom years by avoiding ongoing costs in personnel and new buildings that must be maintained for years to come.

Residents try to adjust, as well. Those who can afford it know to sit on houses and oil equipment until another boom returns. Those in oil and gas trades leverage their skills by fixing equipment or applying them in a different industry.

"I don't know if you ever get used to it," Opella said. "It's tough and sometimes it's painful for a small community to go through."

Opella said he doesn't know if anybody is smart enough to balance the boom and bust cycle of oil. Typically, he said, events will dictate what happens and county officials must make the hard decisions, which usually translates to layoffs.

Overall though, Opella said oil and gas has been a plus for the community. Signs on the sides of buildings or on billboards around town show support, directly or indirectly.

"Oil and gas pay most of our taxes," reads one. "When regulation increases freedom dies," reads another.

Michael Dembro is among the many Casper residents who see the results of oil. Dembro is the kitchen manager at Dori Lou's Restaurant, which lies at the southern edge of town not far from the blinking lights of the Sinclair Oil Refinery and across the street from Halliburton.

Dembro said Halliburton has given the diner-style restaurant a lot of business since he moved to Casper from Boston a year ago. Halliburton's extra crews coming from Texas and Rock Springs, Wyo., Dembro said, have even led to an increase in staffing.

"We have almost doubled, or even tripled, our business from me starting here," Dembro said. "It has given us a good 20 or 30 percent more capital in revenue."

Tom Mast, business editor for the Casper Star-Tribune newspaper, has covered issues relating to oil for years and knows the feel and texture of the booms, as well as the busts. Mast knows the rise and decline of oil and gas isn't a matter of "if," but "when."

"The foundation of this economy has always been oil and gas. It's been here since they opened the Salt Lake field in the late 1800s," he said. "When oil and gas companies sneeze, here, everybody catches a cold."

A major aspect of the instability of oil, Mast points out, is that major declines or spikes in demand aren't necessarily caused by a region's supply of oil and gas.

"There are no guarantees with oil and gas. You are at the mercy of the international markets. That's the bottom line," Mast said.

And this is good and bad. Mast said it also means that during a general recession " such as the previous one " Casper and Natrona can weather the storms much better than most.

During the Great Recession, while states across the country were hit hard, Wyoming and Natrona County unemployment rates stayed low due to oil, Mast said.

According to the U.S. Bureau of Labor Statistics, Natrona's annual unemployment rate for 2008, 2009 and 2010 " not seasonally adjusted " were 2.9, 6.7 and 7.2 percent, respectively, during the start and end of the recession.

Nationally, the annual unemployment during those years was 5.8, 9.3 and 9.6 percent. Weld County's annual unemployment rates for those three years were 5.2, 9.3 and 10.2 percent, respectively.

Mast said the flip side of this is when the price of oil and gas dives, such as in the 1980s. He remembers residents in a panic when oil plummeted to nearly $10 a barrel.

"There were hundreds of houses that were left vacant in Casper. There were bankruptcies. There was an exodus in population," Mast said. "During a bust you may have more than a hundred houses sitting vacant and they may be sitting there for years."

Looking at Weld, both Mast and Opella said economic diversity may be the best defense against over-reliance on energy income.

"Unless oil and gas is big enough to really overshadow everything else that is going on in Greeley " which I doubt very seriously in Greeley " you're not going to have that kind of exposure that Casper has had because your economy is already pretty diversified," Mast said.

According to the well-recited fable, the ants stored their kernels of corn in summer while the grasshopper sang and questioned. Winter came and the grasshopper starved. As the lesson goes: "There is time for work and time for play."

The concept reverberates for Conway, the chairman of the Board of Weld County Commissioners, who said the county has been discussing this long before the recent boom.

Instead of using additional oil and gas money for ongoing costs " such as salaries, county programs and services " Conway said the commissioners have tried to put the funding into reserves, one-time projects such as road projects and lowering homeowner property taxes through temporary tax relief.

Already, due to oil and gas property tax revenues on the roughly 30 oil companies operating in Weld, Conway said homeowners pay on average about $300 less than they normally would, thanks to a temporary refund that commissioners have been able to approve with the budget nearly each year.

"The county believes that if we're able to meet basic needs, then the money should go back to the taxpayers," Conway said. "And if this Niobrara play continues in the direction where it continues to go, I would anticipate in the near future again lowering the mill levy. That would be my hope."

The lower taxes, Conway said, is the county's "buffer" should oil revenues go away, a move that means property taxes could jump during an oil bust if commissioners cannot afford to approve the refund.

Conway said Weld's biggest safeguard is in its programs to stimulate diversification.

"Our whole economic development strategy has been on diversification," Conway said. "One of the concerns that has been expressed for years now is that the county not be too dependent on oil and gas. This discussion was happening in 2005-06."

Weld funds Upstate Colorado Economic Development, an organization tasked to bring businesses to Greeley and Weld. Weld also seeks to entice businesses by keeping taxes low and it supports regional and national economic campaigns to boost incentives for manufacturing and commercial companies.

Freight Rail Works is one such campaign. Conway said it seeks to promote freight rail through tax credits and other economic and regulatory incentives.

Conway said freight rail is an important draw for Weld, which is strategically placed between two long-haul rail routes. Vestas Wind Systems, a wind turbine manufacturer in Brighton and Windsor, is one of many manufacturers drawn to Weld primarily for its rail shipping, Conway said.

"All you have to do is see the train tracks with the blades going north," he said.

And yet despite current and previous efforts to diversify, property tax revenues indicate a trend toward greater oil and gas dependence.

Don Warden, Weld's director of budget management, said when he first took his position about 30 years ago he remembered oil and gas property tax revenues representing only about 20 percent of all revenues. Now, he would not be surprised to see the percentage climbing into the 60 percent range.

Warden is well aware that what goes up, can go down.

"In a matter of a one-year period you can have a spike and then they can drop dramatically," Warden said.

It might be difficult to plan for a bust, but planning for a boom brings its own challenges, too.

A boom can attract a rapid influx of people, traffic, money and crime. The challenge for Greeley and Weld will be to encourage and shape the good " economic development, upgrades to infrastructure, lower taxes " while avoiding the sprawl, vice and growing pains that can follow.

Casper's downtown, like Greeley's, has struggled over the years. It watched the growth in nearby towns with big-box stores, bars, restaurants and hotels springing up on its edges and southward as growth marched along Interstate 25 toward the refinery.

However, Peter Meyers, Casper's assistant to the city manager, said recently they've been able to channel growth back into the downtown area by rezoning the city center into its own district. Meyers said the downtown area, now called the Yellowstone District, was initially zoned as industrial space. The rezoning has opened up the district to residential apartments and commercial businesses, zoning that typically requires higher density limits.

"The proof is in the pudding and we're starting to see a lot of redevelopment," Meyers said, as empty warehouse are turned into renovated apartments, restaurants and commercial businesses.

Meyers said the rezoning has provided the city more balanced economic growth as small towns around Casper, such as Bar Nunn, have experienced notable growth in residential housing.

If the oil investment widens in Weld, as companies like Noble Energy and Anadarko Petroleum have committed to do in the next few years with billions of dollars pumped into operations, this would likely mean planning for an increase of new labor.

But Greeley officials are not worried about meeting a new demand. They're hoping for it.

"I see it as a positive," said Greeley Mayor Tom Norton.

Norton said that even with the oil boom throughout the last few years, population and growth " predicted by the city planning department to average 2 percent from 2011-16 " has not reached excessive levels and there are many parts of Greeley, like its older downtown, that could use business generated by the new demand.

"I don't think any of the growth prediction will be any strain on the city," Norton said. "Greeley is in pretty good shape"

And yet, oil companies are not opening their doors in Greeley's downtown but farther out, and while there is a general plan for growth there is no specific plan for the potential of a dramatic oil boom.

"Greeley's 2060 Comprehensive Plan (the city's long-term growth plan) has projected growth north of the river up to State Highway 392 since the mid-80s and we actually have annexed well over 1,200 acres in this area in anticipation of development in that area," said Community Development Director Becky Safarik. "The biggest impediment to date has not been oil and gas but the cost of extending capital infrastructure into that area."

Safarik said to balance growth within Greeley, officials are promoting the rail corridor as a new industry area, fostering preservation and support of the Poudre River as a recreational and open space amenity and providing economic development incentives throughout the community for qualified businesses, particularly in the older areas.

The oil and oil service companies " such as Noble Energy, which recently announced a new $500,000 storage facility on the west side of Greeley and Halliburton, which announced a Windsor facility to create 500 jobs last January " aren't gravitating toward downtown due to space constraints.

"The oil and gas companies that I've worked with require very large sites, usually to accommodate their offices, but also field crews, equipment, etc.," Safarik said. "So a downtown location in an entertainment district isn't a very logical match. That said, the employees associated with the industry are accessing and enjoying the retail, restaurants and services throughout the community, including the downtown."

Weld District Attorney Ken Buck said crime levels have not shown any spikes, either.

"We have not seen any crime associated with the exploration and production of the Niobrara," Buck said. "We don't have any more crime being committed by the rough necks and drillers than anyone else."

In the 1980s Buck lived in Wyoming and said there has been a major change in both oil company management style and labor, compared to years ago.

"I see a much different attitude. They get along now better with their partners in agriculture and they are much better citizens," Buck said.

Mike Blonigen, the district attorney in Natrona County, said Natrona is again going through a boom, albeit a gradual boom. He said drug testing and better education of employees has cut crime.

"Compared to the boom a few years ago there's nowhere near the same amount of crime," Blonigen said. He acknowledged that oil and gas have contributed to alcohol-related crimes, many involving young workers with lots of money and time on their hands.

Greeley is also monitoring where and how sprawl expands as the city attempts to taper or redirect Greeley's east-to-west expansion.

So far, no oil companies have announced plans to move into downtown Greeley, but the head of Greeley's Downtown Development Authority agreed with Safarik and others that the area is seeing economic benefits already.

"We feel that it's great for the downtown area," executive director Pam Bricker said. "It supports our businesses."

Norton, Conway and Bricker are among those who believe there's every indication the Niobrara boom will continue for decades to come. That would mean Greeley and Weld can look forward to more money, more people and more economic activity. In fact, they're banking on it.

"The law of supply and demand has never changed in our history," Bricker said. "When the demand is there, you grow."