Food and souvenir vendors are parked along 15th Street near Constitution Avenue. (Sarah L. Voisin/The Washington Post)

From her mustard-yellow trailer, she slings the kind of snacks that Americans now dub “guilty pleasures,” if not names even more insulting: hot dogs, candy, jumbo pretzels, frozen pizzas and a rainbow-colored line of sticky popsicles. It’s essentially the same food that Ngoc Phung sold nearly 18 years ago when she first started vending — and the same food that 30-plus other stationary trailers sell on the streets near the Mall.

Business, Phung will tell you, has been slow.

She can’t chalk it all up to the end of tourist season, either. The rot set in years ago, first after the attacks of Sept. 11, 2001, and then following the economic collapse of 2008. In 2009, a fleet of mobile food trucks started rolling onto D.C. streets, many of them parking near her turf without the proper authority to do so.

“Too many trucks come in,” Phung says about the mobile food vendors. “That’s why we don’t make more money.”

But Phung fears her next obstacle will be the one that buries her business for good: Starting in late October, the D.C. Department of Consumer and Regulatory Affairs will assume control of the lottery that assigns the 74 vending locations near the Mall and the Ellipse, a monthly selection process that was previously run by the Metropolitan Police Department. As part of the switchover, DCRA will open the lottery to include not just stationary roadway vendors like Phung but also millennial-friendly mobile roadway vendors, who sell everything from designer cupcakes and crab cakes to kimchi barbecue tacos and Vietnamese pho.

The revamped lottery should immediately transform vending along Constitution Avenue NW and Independence Avenue SW, a pair of wide boulevards that run parallel to the Mall, where more than 25 million tourists a year form their first impressions about street food in Washington. Those same tourists will also find new options along 15th and 17th streets NW, where stationary vendors have dominated the scene for a generation or two.

The changes should help repair the District’s reputation for outdated street food along the Mall, but they may also come at a cost for Phung and her peers. The stationary vendors may soon discover that their business model is obsolete, the victim of evolving tastes and a retooled lottery that they once had all to themselves.

Regardless of the fallout, some critics argue that the changes are way overdue, breaking up what they see as a tight-knit, blood-related group of vendors who have long controlled the streets of downtown Washington with their junk food and tacky souvenirs.

“It’s this little monopoly on street food and souvenirs down on the Mall, which results in nothing that is good for the consumer or good for the impression that the city is giving to visitors,” says Doug Povich, co-owner of the Red Hook Lobster Pound DC truck and chairman of the District Maryland Virginia Food Truck Association.

Down near the Ellipse, the people who work these trailers don’t talk like robber barons of the street vending trade, although several acknowledge they do have family members who also operate food or merchandise vehicles on the Mall. They talk more like people who are resigned to a new reality, one that could squash their business. Mychau Duong, 42, doesn’t know what her future will look like, but the veteran Mall vendor can’t imagine another life for herself. “Too late for me,” she says. “I can’t do anything else.”

For decades, stationary vendors had relied on a low-tech lottery run by MPD. Every month, MPD’s Special Events Branch would conduct two lotteries: one for the 37 spots designated for food operators on the Mall, and another for the 37 spots set aside for merchandise operators. MPD would give each vendor a roadway vehicle number and affix that number to a poker chip. The chips were then drawn at random from a bucket, matching vendor to a location, one by one, until all the spots were taken for the month. It was an antiquated system, akin to drawing names from a hat for door prizes, but vendors trusted it because they could witness the lottery and settle any disputes in person.

It was also a hard-earned trust, says Vivian Nguyen, a 20-year veteran of stationary vending. Back in the mid-1990s, at least two D.C. police officers were arrested for accepting bribes from vendors, who would in return receive a prime location and preferential treatment from police. Two decades later, those memories still linger for some old-timers or their children who have carried on the family business, says Nguyen. They fear that DCRA’s electronic lottery, conducted without any vendor present, will lead to errors and/or manipulations of the process.

“A lot of these older vendors, they’re very worried,” Nguyen says. “Is it going to happen again?”

DCRA promises a fair and transparent lottery, one in which every vendor who registers “will get a spot before anyone gets a second spot,” says Matt Orlins, the department’s legislative and public affairs officer. Unlike the lottery that DCRA operates for the mobile roadway vending zones, the Mall lottery will not permit vendors to check any site preferences.

However the new lottery shakes out, one thing is almost certain for stationary vendors: They will face longer odds for a spot near the Mall. While the number fluctuated month to month, somewhere between 70 to 75 operators on average registered for each of MPD’s two lotteries, says vendor Nguyen. Presumably, the same number will register for DCRA’s lottery, along with an untold number of food truck vendors who want a crack at tourists. As of Aug. 5, DCRA had issued about 305 licenses for mobile food vendors, although some may no longer operate or operate only seasonally, says Vincent Parker, business compliance and vending manager for DCRA.

The increased competition worries Phung, the 43-year-old stationary vendor from Springfield, Va. She fears she may secure only one or two locations in the DCRA lottery, which would translate into approximately four to eight working days a month. “Not enough for us,” Phung says, absently. “Not enough.”

Unlike food truck operators, Phung can’t just drop her trailer at any legal parking spot and vend for a couple of hours until the meter expires. The District allots only those 74 locations for stationary food and merchandise vendors. (It used to be 76, but two spots near George Washington University were reassigned to food trucks because the stationary vendors weren’t using them.) If they want to vend elsewhere, stationary operators will need to apply for a mobile roadway, sidewalk or ice cream truck license and then heed the regulations that apply, including vehicle size restrictions. Stationary vendors would inevitably have to invest thousands to modify their existing trailers or buy a new, self-contained truck.

“We’re trying to wait,” says Nguyen, who represents the stationary vendors, “and see if it’s even worth being in business or just calling it quits.”

Except the loosely organized vendors aren’t just waiting idly for their demise. For a while, they hired an attorney to try to maintain the status quo on the Mall. They even turned to the Mayor’s Office on Asian and Pacific Islander Affairs to help state their case to DCRA; the office, says OAPIA special assistant Dory Peters, provided translation assistance between the parties. And on Monday, stationary vendors sat down with DCRA to hash out their concerns.

The problem is, no one can predict how much new competition the stationary vendors will encounter when the DCRA lottery debuts. Some food truck operators can’t wait to sink their teeth into the fat wallets of those visiting tourists. Others, such as Che Ruddell-Tabisola, co-owner of the BBQ Bus, aren’t rushing to the Mall.

“Our approach to business is [to focus on] the people who come to us week after week,” says Ruddell-Tabisola, also executive director of the DMV Food Truck Association. “When you’re serving to a tourist climate, there is a question of, ‘Will they come back?’ ”

Tom MacDonald, co-owner of DC Slices, is the rare food truck operator who used to run a stationary trailer on the Mall. For about 10 years, MacDonald sold merchandise to visitors, and during the high season, he could pull down between $20,000 to $50,000 a month gross, he says. MacDonald would be willing to give the Mall another go as a mobile food truck, even though food vendors tend to make far less than their merchandise cousins.

“I don’t see why not,” he says.

This summer, some food truck vendors couldn’t wait on the new lottery. They parked on 14th Street NW and other roadways that cut through the Mall. They did so in violation of D.C. law. The rogue trucks may have satisfied some tourist stomachs, but they also irritated their eyes.

“We have had many public complaints about the trucks blocking the view between the Washington Monument and the Capitol and their unsightliness,” says Sgt. Lelani Woods, a U.S. Park Police spokeswoman.

As of mid-September, MPD and U.S. Park Police have made 196 arrests this year for vending without a license on the Mall, a criminal offense subject to a maximum fine of $300 and a maximum jail term of 90 days for each violation, says police spokeswoman Gwendolyn Crump. Since February, DCRA has issued 15 warnings and 26 notices of violation for illegal vending on the Mall, a Class 1 infraction that carries a $2,000 fine on first offense.

People like Povich with Red Hook Lobster Pound DC would like to see more than 74 spots on the Mall for vending, and he may one day get his wish. The National Park Service is developing a prospectus for future food services there. It has been a long time coming: Guest Services, which currently feeds Mall visitors, signed its last contract with the Park Service in the mid-1980s. The contract, which expires in December 2015, gives Guest Services the right of first refusal for any new commercial food services on the Mall. The next contract will not include such a stipulation, which could open up America’s front yard to more culinary options. Right?

“I don’t know,” says NPS spokeswoman Jenny Anzelmo-Sarles. “I’m not going speculate.”

None of this will be welcome news for Ngoc Phung and her colleagues aboard those aging metal trailers. Phung has a photo stored on her smartphone of a food truck that, in August, was parked illegally at the intersection of Seventh Street and Constitution Avenue NW, next to a fire hydrant no less. No one busted the vendor.

“They don’t care,” she says.

The thing is, the District and the National Park Service do appear to care. They just appear to care about giving tourists and locals alike something more than hot dogs, hamburgers, jumbo pretzels, frozen pizza and a rainbow-colored line of sticky popsicles.