CIUDAD HIDALGO, MEXICO — When the migrant caravans cross the Suchiate River and international bridge from Guatemala, Adan Lopez springs into action in this steamy tropical city: He shuts down his shop and takes cover.

Like many merchants along Mexico’s southern border, Lopez, 59, said his business is suffering due to a recent escalation in crime committed by migrants. And many are calling for the Mexican government to shut its doors.

Lopez, 59, owns a stall selling blue jeans in this city of nearly 15,000 people on the southern tip of Mexico. Since last October, thousands of mostly Central American asylum-seekers have overwhelmed the city, which is just steps from a bridge connecting Mexico to Guatemala. With no other place to go, many camp out in the town square and beg.

“We know they are not all bad people, but when they started to come through, there were suddenly a lot of robberies and assaults,” Lopez told The Post. “So now, when we get a multitude crossing the border, we just close the shop.”

At first many tried to help the migrants by distributing food and water, but when they started arriving by the tens of thousands, local merchants were overwhelmed.

“They asked for things but we can’t help everyone,” said Imelda Estrada Garcia, who owns an outdoor restaurant in the town square, where recently arrived migrants from Central America and Haiti beg for food and water.

“We have a lot of migrants and they’ve caused a lot of problems here,” Garcia, 61, told The Post. “They’ve robbed and assaulted people. We have a dead person here, a dead person there. They are constantly begging and they urinate in the street. We know they are human beings but we don’t want them here anymore.”

Garcia and a group of local women recently organized a protest against federal authorities who wanted to convert the local secondary school into a migrant camp.

“Our children go to that school,” she said. “How could they put people who are maybe bringing diseases, who could be criminals ?”

The sentiment is echoed throughout the border communities in Chiapas, one of Mexico’s poorest states. In Tapachula, a city surrounded by coffee plantations that is about 40 minutes north of the border, the addition of more than 10,000 migrants has brought gangs such as MS-13 and Barrio 18 from Central America.

Of the 462 migrants spread out in 53 jails across the country, 268 are in Chiapas prisons, according to statistics collected by state and federal law enforcement. Many are awaiting trial, accused of homicide, robbery, extortion, rape, kidnapping and drug trafficking, among other crimes.

The spike in crime is forcing shopkeepers to close before dark in Tapachula and keeping tourists away, according to local tour operators and merchants.

“It’s sad what’s happening in Chiapas,” said Alexander Fleck, who runs Nativa Tours in Tapachula. “We cannot receive in our home people who we don’t know anything about.”

Last week, the regional chamber of commerce accused the Central American gangs of committing most of the city’s crimes.

“They are a huge problem,” said José Antonio Toriello Elorza, president of the Confederacion Patronal de la Republica Mexicana, in an interview with El Orbe newspaper last week. He blamed the gangs for seven out of every 10 crimes committed in the region.

The situation has gotten so out of control that a Guatemalan conglomerate that planned to invest $280 million in a palm oil refinery in the region is having second thoughts because of the escalation in crime, Toriello told the paper.

“We have a lot of problems at the southern border,” he said. “We are truly sad that this could cost us the development of the entire region.”

With no place to stay and few resources, thousands of migrants camp outside a federal immigration detention center in Tapachula, waiting for documents to allow them to cross through Mexican territory. Some live in the main city square, where they hang their wet laundry on park fences and sleep on sidewalks.

At the immigration center, pregnant women lie on the concrete pavement and desperate parents beg passers-by for food for their children as mangy dogs roam the crowd. Last week, dozens clambered around a blue pickup carrying crates of bananas that were being handed out by a local priest.

When The Post visited Ciudad Hidalgo on Saturday, there were two dozen migrants camped out in the open-air amphitheater in the main square, and dozens crossing the international border.

José Antonio Lopez, 51, who had recently arrived from Honduras with his family, said he could feel the tension as soon as he crossed the bridge in Ciudad Hidalgo. He hoped to travel to the United States, where he has family in Georgia and Florida.

“Because of a few delinquents, all the migrants have to pay for it,” he said.