A city with 40,000 vacant buildings and lots has plenty of space for businesses to develop. Yet Philadelphia entrepreneurs are choosing a distinctive form to set up shop--the truck.

While lunch trucks have dotted the streets of populated areas and college campuses for more than 30 years, the trend has grown in recent years to include high-end food trucks that serve local fare, trucks with brick ovens, trucks with lights strung all over, trucks that teach gardening, trucks that'll fix your bike, trucks that will make you sushi and even a truck that serves as a mobile museum.

In one year from 2009 to 2010, the mobile food industry grew nearly 7 percent while the food industry as a whole grew 1.5 percent. And it's forecasted that food trucks will quadruple to 4percent of industry sales by 2017.

When did this truck fad start? What is it about trucks that enamore and attract us as opposed to the storefronts in our neighborhoods? Is this unique to Philly? Are entrepreneurs turning to trucks to save money? Or is this a change in the consumer--do we not have time to stop, sit down and enjoy a meal? What is the recipe for the truck trend?

Start with three heaping cups of recession.

Erin Bernard is the founding director and chief curator of Philadelphia's own public history truck which began its first exhibit cycle this year in East Kensington. This pasty white truck is a mobile museum.

"At its core it's an access project in terms of cost and location," Bernard explained, "But also in process."

The museum on wheels doesn't just come to you to save transportation and admission fees, it brings you history curated by the community. Whether recording oral histories or helping to build exhibits, Bernard and 'Kensingtoners' are archiving to share their history across a city that often condemns their neighborhood.

"My hope is that a bunch of neighbors that didn't already know each other [will] know each other," Bernard said.

While the idea may seem revolutionary, mobile history is not new, according to Bernard. In the midst of a recession and education crisis in 1982 (sound familiar?) a group of historians decided to start a history mobile in Philadelphia. However, funding issues killed the engine of the plan. But the idea was planted, perhaps more telling of the primordial soup that is a recipe for entrepreneurial innovation--crisis.

"Doctoral students didn't have places to work," Bernard explained, "There was a funding crisis for the arts."

And here we are in 2013, recovering from a massive recession with a cohort of unemployed youth and a struggling school district--perhaps just the right ingredients for an alternative plan.

Trucks may be more accessible, but a huge drive for entrepreneurs is their affordability.

Honest Lou's & Sons Extermination Supply Co. might not be the image at the forefront of the truck trend--people generally don't like to think about roaches, fleas, termites, bed bugs and rats. Yet these images are pasted right on the side of the bright yellow and blue truck parked on an island surrounded by the sea of traffic from Broad Street, Erie Avenue, Germantown Avenue, and Butler Street. Honest Lou's is a ship happily docked without any plans to sail let alone set foot on land.

James Lougl said that the 50-year-old business has been operating out of the truck for six years. When rent prices rose, the business model shifted.

"It's convenient," Lougl explained, "You don't have the overhead of property. You eliminate electricity."

With no rent, upkeep, utilities, cheaper taxes and a prime location, the truck has served the business well, according to Lougl.

More and more, entrepreneurs are catching on.

The National Restaurant Association estimates that food trucks generate $650 million in revenue annually. But in a billion-dollar industry, food trucks make up less than 1 percent of sales. However, Intuit, the American software company that brought you TurboTax, released a report predicting a quadrupling of food truck industry sales by 2017.

The same report estimated that the average startup cost for a brick-and-mortar restaurant is a quarter to half a million dollars while a food truck can open its mobile kitchen for about $50,000.

Annika Stensson, the senior manager of research communications at the National Restaurant Association, explained how food trucks can compliment establishments that often feel threatened by trucks' gaining momentum.

"They have gained in popularity across the country throughout the last several years," Stensson explained. "Trucks can be a good way for entrepreneurs to start out in the restaurant business if financing is tight."

Stensson also sees trucks as a way for current businesses to expand operation to serve a new area of customers, "beyond the four walls of their restaurant." 

A National Restaurant Association survey cites that 73 percent of adults would visit a food truck by their favorite restaurant, according to Stensson.

Yet trucks offer a unique experience, affordability and convenience that might just beat out brick-and-mortar restaurants.

Five tablespoons of convenience

A 2011 survey from the Academy of Nutrition and Dietetics reported that 83 percent of Americans eat at their desks while working, opting for pack or take-out lunches more often than a sit-down restaurant. But the ease of a quick and cheap meal is just one aspect of truck convenience. 

Non-food trucks are cropping up across the city, from the Breakaway bike repair trailer at Temple University to the United States Department of Agriculture's plant truck that visited Philadelphia's Eakins Oval this past summer. A truck can park where it's needed, when it's needed, to find its customers. And follow the customer on Twitter.

Connecting to customers through social media has proven successful for Philadelphia trucks like Vernalicious and Cow and the Curd, both who have about 2,000 Twitter followers and 1500 Facebook likes. The trucks interact with their customers online and on location.

Philadelphia also helps to fuel the truck and customer relationship by essentially throwing enormous networking events in neighborhoods across the city.

The Food Trust's Night Markets have brought bustling crowds to Fairmount, West Oak Lane, Chinatown, South Street, Passyunk and Mt. Airy. West Oak Lane's Night Market in June 2013 attracted trucks and residents from Center City to Northwest, Philadelphia.

A business on wheels can reach different neighborhoods without committing to them. While trucks are booming, neighborhoods remain plagued with blight and lack of investment.

The same wheels that drive business to neighborhoods can also drive away.

A slice of niche, a pinch of Philadelphia

Erin Bernard thinks that there is something about a truck, as opposed to a lemonade stand, a car or a building.

"People do things in a niche way," Bernard mused, citing the popular retail site Etsy as a microcosm of a global trend towards catering to each customer's specific needs. Etsy provides a platform for individuals to sell their handmade or vintage products through an aesthetic reminiscent of the Racked traveling clothing trailer which has parked in Rittenhouse and University City this past fall.

"It's a little website, on site," Bernard concluded.

The history truck likewise attracts attention.

"People love it so much, so quickly," she explained, "people can relate to trucks."

A shiny refurbished food mobile reaches the masses just as a politician rolls up her sleeves to work a room, trying to compensate for being overly polished. But there's something more legitimate about Bernard's truck. It doesn't hide its past under coats of paint. It once delivered mail, then water ice and now it parks outside row homes in East Kensington. There's something Philly in the public history truck. This is a city where you can reinvent yourself, but never lose your roots and your community.

"It's an entrepreneurial city," Bernard explained, "There is a brave spirit."

And not a spirit and mind catered to gentrified millennials, either. As Bernard puts it, the most common thing she hears after explaining the trucks mission is, "how did I not think of that?"

United States food trucks have travelled across generations and segments of the population, feeding 2012 Super Bowl fans in Indiana and taking center stage in a Food Network reality series.  

Food trucks aren't a trend prancing hand-in-hand with a recent urban influx of "localvores". Corporations like Chick-fil-A and Applebee's have launched food trucks in Washington, D.C., and Denver, respectively.

Philadelphia's truck scene has remained fairly uncluttered by the corporate world, yet still significant. In 2011, Philadelphia had the third largest number of food trucks in the country behind New York and Los Angeles, according to the U.S. Census.

George Bieber started the Sunflower Truck Stop after establishing Shorty's Sunflower Cafe in Pottstown, PA. His cafe is now busier than ever. Bieber credits the truck.

"It allows me to reach out to a different group of customers," Bieber explained. "It's a great vehicle for growing your business."

After recognizing a need to form a voice for the truck community, Bieber along with entrepreneurs came together to start the Philadelphia Mobile Food Association in 2012. Last May, the association had 36 members. Now they're up to 96. At a rate of gaining 2 members a month, Bieber hopes to reach 125 members by the end of next summer.

Bieber sees trucks as a new phenomenon on the East Coast that sparks the interests of the young and old alike.

"I notice a lot of older people coming to the truck. For me, it's not your typical college students," Bieber explained.

But the Philadelphia Mobile Food Association skews young and Bieber, 45, "might be at the top end."

Truck owners aren't just individual entrepreneurs, either. Bieber described couples, trios and old friends coming together to run a business.

"There's so much potential," Bieber said, adding that like the entrepreneurs, food trucks are at, "a very young stage of things." 

Again like the owners, Philadelphia's truck fare is diverse. Poi Dog serves Hawaiian food, Cherry Bomb Bus serves tacos and carrot cake, Brazbq combines Brazilian with barbeque and Foo Truck cooks up Asian-inspired fare. Carribean, Korean, Indian, Soul or Halal, Philadelphia has it.

According to the 2007 Census, 81 percent of all food truck owners surveyed in the United States identified as white. Seven years later, that trend could be shifting as more individuals find a niche market.

The National Restaurant Association released a report that predicted greater diversity in the industry's workforce by 2020. Today, less than 22 percent of chefs and head cooks are women, although almost 19 percent of chefs surveyed identified as Latino, according to 2012 averages from the Bureau of Labor Statistics.

An optional teaspoon of hype

Street food has been a trend long before the engine was invented and food trucks have served Philadelphians for more than half a century. The fresh paint on the food truck industry may just be a makeover.

Trucks may serve sustainably-produced meals, but their wheels call into question their commitment to this city. The same mobility and accessibility that popularized trucks could allow them to pursue markets elsewhere.

Yet even corporations with solid foundations in this city, like Citibank and Sunoco, have decided to abandon and consolidate outside of Philadelphia.

The trend can only continue as long as the city breeds and attracts entrepreneurs. Only time will tell if food trucks are a recipe for disaster.