First there was the Trump administration’s travel ban, then talk about the Mexican border wall and, finally, last week, Alfredo Solis decided it was time to send a message. So the owner of Mezcalero, the hottest new Mexican restaurant in the District, put it at the bottom of his receipts: “Immigrants help make America great!”

“I came to this country 17 years ago, and I work hard. I want to help make America great,” said Solis. “America is great already.”

Around the same time, a customer in San Antonio used a receipt to send a very different message. After a meal at Di Frabo, a local Italian restaurant, the customer wrote on a receipt: “The food was tasty and the service was attentive. However the owner is ‘Mexican.’ We will not return. ‘America first.’ ”

Di Frabo’s owner, Fernando Franco, isn’t sure who shared the image with the media after his wife posted a photo of the receipt to her private Facebook page. But it’s been difficult for his business ever since.

“We had to turn off the phone for two days,” he said. “We had employees who left because they felt very overwhelmed by the phone calls and some threats.” His kids were so afraid, they stayed home from school for a few days. And the media attention has scared off some of his customers.

“I have been in the restaurant business for 15 years. I have restaurants in Mexico, and this one in the U.S.,” he said. “I never experienced something like this before.”

We fight about politics on Twitter and in the comments section; we wear our political beliefs on hats, whether they’re red baseball caps or pink knitted and pussycat-eared. We shop, or don’t shop, at stores that carry, or don’t carry, Trump-branded merchandise. We argue over Starbucks cups, for crying out loud. And the culture wars have pushed forward to their newest battleground: the receipt.

“Receipts have always been a place where you can talk back and forth,” said Brian Warrener, an associate professor at Johnson & Wales University’s School of Hospitality. Sometimes they come with a comment card, sometimes your waiter will draw a smiley face, sometimes a customer will write “Thanks!” next to their tip. The difference now is that political dialogue has become more heated. “It’s a matter of extending that coarse discourse that exists out there, into a place where coarse discourse never really existed.”

To the restaurateurs who are putting messages on their receipts, it might seem more effective than an “Immigrants are welcome here” sign on the door, or a Langston Hughes poem on the menu. The menu is in diners’ hands for only a few minutes — and they’re probably more invested in deciding between the chicken and the lamb than in reading about politics. But the receipt, if they take it, follows customers home.

That doesn’t necessarily make it a more effective messenger, Warrener says. For restaurants posting pro-immigration messages, it’s really about showing solidarity to their staff, which may be led by immigrants. The industry employs 1.8 million foreign-born workers, according to the Bureau of Labor Statistics.

“I don’t think a restaurant is necessarily going to flip anyone’s opinion about immigration, but it might make them feel better for a period of time,” Warrener said.

That was part of the reason chef Mark Simmons of the Brooklyn restaurant Kiwiana began printing a pro-immigration message on his receipts: “Immigrants make America great (they also cooked your food and served you today).”

“I could see that some of the people on my team were a little unsettled,” said Simmons, a “Top Chef” alum who immigrated to the United States from New Zealand. “I wanted to make my team feel like I got [their] back. This is how we feel. We’re going to make a stand.”

When a journalist tweeted a picture of her receipt last week, the message went viral — bringing Simmons an onslaught of feedback, both positive and negative. He characterized most of the calls and notes as “heartwarming,” and his staff has enjoyed an increase in tips and an uptick in business in liberal Brooklyn. But he’s also gotten a lot of flak from faraway Trump supporters.

One caller from Missouri said she was boycotting the restaurant. “I said, ‘Have you ever been to my restaurant?’ She said no,” said Simmons. “I will not lose sleep over this.”

Receipt messages may also point to a baser instinct. The receipt is the final interaction between the restaurant and customer, so whoever gets their message across on a receipt is essentially getting the last word. But that interaction might be weighted more toward the customer, who can punish a restaurant by leaving a nasty message and withholding a tip. In August, a couple in Harrisonburg, Va., wrote “We only tip citizens” on their receipt at a local eatery. Their waitress, 18-year-old Sadie Karina Elledge, is of Mexican and Honduran descent but was born in the United States. The story made headlines across the country.

It’s also why Franco was especially shaken by the message his customer left on his receipt. He would have been less bothered by the same message left on Facebook or Yelp, he said, because “You have no idea if they really were at the restaurant, or who they are,” he said. But when someone scrawls their political beliefs on a receipt, “It’s more immediate. It’s someone’s handwriting,” said Warrener.

It also feels like a bellwether to greater fears in the restaurant industry about immigration. Franco is in the United States on an investor visa, which must be renewed frequently. He has been here four years, but under the current political climate, he is not sure whether he will be able to stay.

“We are now looking … to open another restaurant in Canada, and trying to have that option in case something happens here,” said Franco. “You don’t know what’s going to happen. You can’t really make a plan for the future because you don’t have any idea what’s going to change tomorrow.”

A similar sense of worry has overtaken Solis, who has a green card.

“I hope people understand when they come to my restaurant that I can’t not say anything,” said Solis, who plans to put the same message on the receipts at his other restaurant, El Sol. “I don’t feel safe.”

So, in a way, Solis’s pro-immigrant receipt message is a way for him to make his restaurant a safe space. Sometimes, that sense of safety can come from customers, too. Warrener pointed to the Trump voter who came to Busboys and Poets after inauguration and tipped his African American waitress $450 on a $72.60 bill, with a note: “We may come from different cultures and may disagree on certain issues, but if everyone would share their smile and kindness like your beautiful smile, our country will come together as one people. Not race. Not gender. Just American. God Bless!”

That’s the kind of dialogue Simmons is hoping to start.

“What I love about America is you do have freedom of speech and you feel comfortable making a statement,” he said. “Hopefully we can have a conversation about it.”