This story originally aired on March 27th, 2007.
If you ever find yourself in Dallas, follow the sounds of traditional Mexican music (and the smell of fresh pizza) and you might wind up at a tiny restaurant tucked away in a Dallas strip mall.
While the Pizza Patron, as this chain is called, does not stand out, it does have one rather unique quality. Discreetly placed on the counter is a small sign that states Pizza Patron now accepts pesos, the Mexican currency, along with U.S. dollars.
Watch the full story tonight on 'Nightline' at 11:35 p.m. EDT.
Nearly all of the restaurant's customers -- no matter their heritage -- still pay in good old U.S. dollars, but the fast food chain says that at least 5 percent of their patrons exchange pesos for their pizzas.
Behind every counter, store employees consult a chart explaining exactly how to convert the currency, based on the exchange rate of roughly 12 pesos to the dollar.
The idea of exchanging pesos for pizza began in January as a holiday promotion for customers returning from their Christmas visits in Mexico. When they returned, they could spend their spare pesos at the Pizza Patron.
However, the idea became so popular that it now remains a regular feature at all 64 Pizza Patron outlets. The chain's eateries are mostly in the Southwest, not necessarily along the border, but in heavily Hispanic cities like Dallas, Denver, Las Vegas and Los Angeles. Additionally, the campaign has now become a lightning rod in America's immigration debate.
"We wanted to say to our customer, 'Look, we understand you,'" said Antonio Swad, CEO and founder of the chain. "We understand that you might have some pesos that you want to exchange for pizza and we're the place to do that."
Swad said the plan immediately attracted new customers. "Yeah, it was exactly the right thing for our customers," he said. "It was a way for us to reach out and to do a better job of serving our customer than maybe some of our competitors do."
"From the beginning, I was driving to work on Monday morning and noticed that all the talk radio stations were talking about this," Swad said.
And not everyone was thrilled with the plan. At company headquarters, mail and e-mail came pouring in, and at first, nearly all of it was negative.
One e-mail said, "[You] should not accept pesos. This is America, not Mexico. As if the immigration problem were not bad enough, you people have to accept Mexican money which makes it look like we are accepting this problem instead of fighting illegal immigration."
A voice mail said, "Your attempt to Mexicanize our country by advertising the fact that you accept pesos -- it's an insult to all of us. You want to accept pesos, move your ass to Mexico."
Advocates of tougher enforcement complained that accepting pesos undermined American culture.
"We are having to encounter so much that is not America anymore, that's not the United States," said Jean Towell, president of Citizens for Immigration Reform, a group in Dallas. "We are inundated with having to read everything in two languages. We are having to deal with so much, giving over to people that are not citizens, that are here to have jobs."
The staunch opposition to pesos, however, does not apply to foreign currency from Canadians in the north.
"I guess the difference is that we don't see Canadians coming over in droves and taking our jobs," Towell said.
But Swad is not concerned with knowing which of his customers are American citizens and which are illegal immigrants.
"You know, we're in the restaurant business," he said. "We serve everyone that wants a pizza and has the money to pay for it."
Like so many American success stories, Pizza Patron started simply enough, with one tiny pizza parlor in Dallas. Its original name was Pizza Pizza, just so no one could mistake its one and only product.
When Swad noticed nearly all of his customers were Latino, he changed the name to Pizza Patron, essentially hanging out a "welcome" sign to the Hispanic community.
"Patron means a benevolent leader of the community. The first time I heard that, I thought, man, I like the way that sounds," Swad said.
In a hotly contested business, with competitors on nearly every corner, such Hispanic-friendly touches helped target a rapidly growing market.
Even Wal-Mart accepts pesos at some of its locations near the Mexican border, cell-phone companies such as Movida cater exclusively to Latino customers, and Spanish-language marketing has exploded across American media.
For Pizza Patron, the great pesos controversy has produced some unintended consequences.
E-mail traffic is now running about even between positive and negative messages. Swad, whose own background is Lebanese and Italian, has become something of a hero in the Hispanic community for not backing down to his critics.
"We've had a lot of comments," he said. "People saying, 'You know what? You're not afraid. You didn't back down with all the heat.' So, by not backing down that's a way of sticking up. So we're not gonna sell out our customers."
The campaign appears to be working. The company boasts that business since January has jumped 34 percent over the same period last year, a bump that it attributes in part to the buzz surrounding Pizza for Pesos.
It plans to open many more outlets in the next few years. Pizza Patron is an old-fashioned example of one company finding its niche, capitalizing on opportunity and cashing in.
ABC News' Eric Johnson contributed to this report.